Air chamber type patient mover air pallet with multiple control features

ABSTRACT

Air chamber-type air pallets incorporate side-to-side linked air pressurized tubes or chambers in two integrated rows, having common members for adjacent chambers under air pressurization rendered rigid over a certain extent to rigidify the air chambers thereof which form load backing chambers in place of rigid backing members conventionally employed in air pallets maintaining the load footprint borne by the air pressurized backing chambers matched by that of the developed air bearing or air film by passage of compressed air through the pattern of perforations. Preferably, linked tubes of one row are laterally offset but integrated physically to those of a second row to both limit lateral shrinkage of linked tubes extending completely across the pin hole perforations within the thin, flexible bottom sheet partially forming such air pallets. The use of upper and lower rows of tubes subject to air pressurization provides adequate separation between the load and the fixed support surface to prevent contact of the load and the fixed support surface irrespective of loss of pressurization of a given one of the tubes of either row. The air pallets are formed totally of thin, flexible sheet material, permitting deflation and transfer from one locale to another. The air pallets function as stable supports for the patient during transport over the developed air film between the patient mover and an underlying fixed support surface. A single row of linked tubes formed of two thin, flexible sheets, acting as plenum chambers and having perforations within the thin, flexible bottom sheet functions adequately to support the patient directly on the top thin, flexible sheet with the bottom tangential surfaces of the individual tubes flattening. Preferably the area of perforations for each tube is limited transversely to the flattened portions of those tubes facing the underlying fixed support surface, with the developed air film having a surface area matching that of the patient.

FIELD OF THE INVENTION

This invention relates to air pallets, and more particularly to airpallet-type patient movers for facilitating comfortable support of andtransfer of patients and more particularly to a semi-rigid air pallet inwhich a series of parallel, compressed air filled tubes or the like formone or more backing chambers which function as a generally rigid backingmember.

BACKGROUND OF THE INVENTION

The present invention is an outgrowth of the development of an airpallet using low pressure, low cfm air flow exemplified by U.S. Pat. No.3,948,344 entitled. "LOW COST PLANAR AIR PALLET MATERIAL HANDLINGSYSTEM" issued Apr. 6, 1976, and U.S. Pat. No. 4,272,856 entitled,"DISPOSABLE AIRBEARING PATIENT MOVER AND VALVE EMPLOYED THEREIN", issuedJune 16, 1981.[., assigned to the common assignee.].. Planar air palletsand air-bearing patient movers of such type employ at least a thinflexible bottom sheet for partially defining a plenum chamber, with saidone sheet being perforated by way of small, closely spaced pin holesover a surface area defined by the imprint of the load, which pin holesface an underlying fixed, generally planar support surface. The pinholes open unrestrictedly to the interior of the plenum chamber and tothe planar support surface. When the plenum chamber is pressurized bylow pressure air, initially the air jacks the load upwardly above thethin flexible sheet, then air escapes under pressure through the minutepin holes and creates a frictionless air bearing of relatively smallheight between the underlying support surface and the bottom of theperforated flexible sheet.

In all air pallets, including patient movers, it is necessary to providecontrolled pillowing of the thin, flexible sheet material, particularlyoutside the perforated surface area of that sheet to initially jack theload above the flexible sheet prior to the creation of the frictionlessair bearing and to insure the ability of the air pallet to ride oversurface projections on the underlying support surface. Means must alsobe provided within the air pallet to prevent ballooning of the thinflexible sheet or flexible sheets defining the plenum chamber wherebythe plenum chamber takes a circular or near circular vertical crosssection, the result of which could be the tilting or rolling of the loadoff the top of the air pallet. Further, when the load rests on the airpallet, prior to the pressurization of the plenum chamber the load tendsto press the perforated flexible sheet into contact with the underlyingsupport surface which prevents the entry of air under light pressureinto the plenum chamber. Thus air dispersion means are required eitherinteriorally or exteriorally of the plenum chamber to ensurepressurization of the plenum chamber.

Under certain circumstances, the load may additionally constitute agenerally rigid, i.e., semi-rigid backing member. A cardboard box filledwith material for transport may have the planar bottom functioning as agenerally rigid backing member. Where the air pallet is formedessentially of a thin flexible sheet material bag, a bag of grain actingas the load may constitute a generally rigid backing member.

In the development of air pallets and in particular air bearing patientmovers as a form of such air pallets as exemplified by U.S. Pat. No.3,948,344, a corrugated sheet such as sheet 34 within the single chamberfunctioning as a plenum chamber in a patient mover formed by twosuperimposed thin flexible sheets 12, 14 in U.S. Pat. No. 4,272,856 mayconstitute both a unitary air dispersion means and a semi-rigid backingmember (if needed). The semi-rigid backing member may comprise asemi-rigid sheet inserted within a cavity formed between the top thinflexible film sheet and an intermediate thin flexible sheet.Alternatively, the backing member may be formed of a series oftransversely linked air pressurized tubes formed by sealing offparallel, laterally adjacent longitudinal sections of the top sheet andthe intermediate sheet. Such tubes may be completely sealed and airpressurized through valves. In a flowthrough system, the pressurized airforming the air bearing passes first through parallel, transverselylinked tubes defined by the top and intermediate sheets and then intothe plenum chamber defined by the intermediate sheet and the bottomsheet with the bottom sheet bearing the pattern of perforations over thefoot print of the load. U.S. Pat. No. 4,528,704 issued to Jack Wegenerand Raynor D. Johnson, co-applicants herein on July 16, 1985 andentitled .[.Semi-Rigid Air Pallet Type Patient Mover.]. .Iadd.SEMI-RIGIDAIR PALLET TYPE PATIENT MOVER .Iaddend.is directed to such air pallets.

Flow-through chambers connected by succeedingly smaller sized portswithin horizontally extending vertically spaced walls define a series ofstacked chambers in a gas pressurized jacking structure and an airpallet including such jacking structure and forms the subject matter ofU.S. Pat. No. 4,417,639 issued to Jack Wegener, a co-applicant herein onNov. 29, 1983 entitled, "DYNAMIC GAS PRESSURIZED JACKING STRUCTURE WITHIMPROVED LOAD STABILITY AND AIR PALLET EMPLOYING SAME". Further, asevidenced in FIG. 10 thereof, such jacking structure may be formedtotally of thin flexible sheet material with vertically separatedchambers in communication via a gas passage whose cross-sectional areais smaller than that of the air inlet to the upper chamber thereofthrough the air inlet hose.

In the semi-rigid air pallet type patient mover of U.S. Pat. No.4,686,719 .[.assigned to the common corporate assignee.]. and entitled"SEMI-RIGID AIR PALLET TYPE PATIENT MOVER", U-straps are sewn to thelateral sides of the patient mover structure for facilitating lateralshifting of the patient placed thereon with the plenum chamber gaspressurized and a thin air film underlying the perforated area of thethin flexible bottom sheet. The patient may be bound to the top of thepatient mover via a pair of crossed VELCRO® hook and loop materialcovered straps for ease in engagement and disengagement of the strapends about the patient.

In the field of air pallets and particularly of the patient mover typethose patient movers formed of multiple, thermal bonded or stitchedsheets of thin flexible sheet material which incorporate a rigid or asemi-rigid sheet as the load backing member are not universally employedwithin the hospital or other treatment facility. The existence of therigid or semi-rigid sheet carried within a pocket or cavity defined bytwo thin flexible sheets renders the assembly bulky. and addsconsiderably to the weight of the same. While such patient mover mayperform extremely well at a certain hospital station or treatment areasuch as facilitating patient movement onto and from an X-ray machine,the patient mover remains at that area and is unlikely to be employed inmoving the patient to and from the hospital bed remote from the X-rayarea since hospital personnel resist transporting such patient moverfrom location to location.

The same is true where the air pallets such as patient movers areutilized by paramedics, shock trauma units or the like. As a result,recently there has been shown considerable interest in the developmentof soft pad or hard pad air chamber type air pallets as patient moversor as patient positioners devoid of such rigid or semi rigid sheet. Inthe health care field, particularly the person transported or changed inposition in many cases is not truly a patient recovering from sicknessbut, one requiring continuous attention, such as an invalid or partialinvalid. In this case, upon either transport, or positioning andmaintaining the patient comfortable in a given partially upright orsupine position, the possibility of a tissue breakdown exists with theneed for inducing therapy during the time that the patient remains insuch given positions for a significant period of time. Essentially,there exists the need for the prevention of skin breakdown which canoccur within a very short time whether the patient is in a health carefacility or hospital, even while on the operating table of suchhospital.

The applicants have determined that there are significant differencesbetween the rigid back air pallet and the flexible or air chamber typeair pallet with a load that can flex. In the development of air palletsand air pallet-type patient movers utilizing a thin, flexible bottomsheet partially defining a plenum chamber and being perforated by way ofthousands of small, closely spaced pin holes over the surface areadefined by the imprint of the load and which open unrestrictedly to theinterior or the plenum chamber and to an underlying planar supportsurface, such air pallets and air pallettype patient movers havegenerally employed a rigid backing member starting with U.S. Pat. No.3,948,344. Exceptions lie in the patient mover of U.S. Pat. No.4,272,856, and in the patient mover illustrated in FIGS. 4 and 5 of U.S.Pat. No. 4,528,704.

Certain structural features and parameters with respect thereto play avery important part in the successful operation of an air pallet havinga rigid backing member. The first consideration and operating parameteris that of load distribution. By taking the weight of the load anddividing it by the mass load footprint area in square inches, oneobtains the value of the air pressure in pounds per square inch requiredto lift the load and to move the load on a developed air film by theescape of air from the perforations. By multiplying the width of theload times its length, one obtains the value of the footprint of theload in square inches. The plenum chamber in such structure is usuallydefined by the rigid backing member and the thin flexible bottom sheetbearing the perforations. The area of the plenum chamber footprint insquare inches is the length of the plenum chamber multiplied by itswidth. The key for successful movement of the load on a developed airfilm by air escape from the perforations is to make the air work on theload and to control the action of the air in doing that job. By matchingthe footprint of the load to that of the plenum chamber pattern area ofperforations, thus generally matching the area of the developed air filmto that of the load, the air pallet with the plenum chamber pressurizedwill jack the load, create the air bearing and permit the load to bestably moved on the air pallet.

If the mass of the load is through spread through too small an areaagainst the plenum chamber, i.e., point loading, the load may ground outthe portion of the plenum chamber between that load and the underlyingplanar support surface causing the thin flexible sheet to bulge outaround the point load application against the top of the plenum chamber.Thus, with the plenum chamber up and about the sides of the load, theload is not lifted, the air does not escape through the perforations andno effective air bearing is created.

When the load footprint is less than the plenum chamber air filmfootprint, a significantly greater pressure is needed to lift the load.

Successful operation of rigid backing surface type air pallets requirescontrolled jacking, controlled pillowing and anti-ballooning. Control ofload distribution may be achieved by the use of a rigid backing membersuch as a board or sheet as part of the plenum chamber, or within aseparate chamber supporting the load but overlying the plenum chamber.The rigid backing member distributes the load mass balanced equally overthe area of the plenum chamber footprint. The control of the plenumchamber can be performed in several ways and a properly designed plenumchamber can effect several of the control functions, i.e., jacking,pillowing and ballooning.

The term "jacking" covers the act of raising the load so that air canenter into and be distributed throughout a plenum chamber, or multipleplenum chambers, and then pass out through the perforations to form theair film or air bearing while permitting the planar rigid backingsurface to support the load and allow it to move on the film of air.

The term "pillowing" describes the ability of the thin, flexible sheetto deform so as to ride over or under surface irregularities in thegenerally planar support surface (ground, floor, etc.) without bottomingout. If the compressed air within the plenum chamber does not jack theload high enough, the rigid backing member will ground out against thethin, flexible bottom sheet and the surface irregularity (verticalprojection).

The term "ballooning" covers the situation where the load is jacked orraised up so high that the load becomes unbalanced on the footprintformed by the plenum chamber. This is normally caused by the thin,flexible sheet tending to become hemispherical (where a generally rigidplanar backing member acts in conjunction with the thin, flexible bottomsheet bearing the perforations to form the plenum chamber). Thehemispherical configuration given to the thin, flexible bottom sheetpermits it to roll about the curved surface tilting to the extent wherethe load may be dislodged. As may be appreciated, the pillowing controlfunctions as an anti-ballooning means. Absent the generally rigid planarbacking member, where the plenum chamber is formed of thin, flexiblesheet material such as a bag, the bag will take a circular cross-sectionwhen fully pressurized, the true essence of a balloon.

Where the thin, flexible bottom sheet is tightly mounted at oppositesides to the generally rigid backing member that rigid backing memberfunctions to control jacking, pillowing and ballooning. Where the rigidbacking member is smaller than the thin, flexible bottom sheet, slackdevelops within the thin, flexible bottom sheet which increases thepillowing capability of the thin, flexible bottom sheet. Excessive slackleads to ballooning.

Other means have been provided for controlling pillowing, such as thelamination of additional members to a center sheet or to either theupper thin, flexible sheet or the bottom thin, flexible sheet. Theaddition of internal strips lying diagonally from corner to cornerwithin the plenum chamber or vertical from face to face, control thedegree of pillowing. The load itself may act as a pillowing controlmeans. The insertion of a rigid plate internally within a thin, flexiblebag acts both as a rigid backing member, a pillowing control means andunder certain conditions air distribution means for insuring airpressurization of the plenum chamber with the air pallet formedprincipally by the bag supporting the load prior to air pressurizationof that plenum chamber. The size of the blower and thus the air pressuredeveloped within the plenum chamber may constitute pillowing controlmeans, as may valving or gating of the air flow system entering theplenum chamber and creating the air bearing, and the stiffness orflexibility of the material used in forming the thin, flexible bottomsheet. The area of the material around the perforation pattern andbetween that pattern and the rigid backing member is normally theprimarily pillowing control means for such air pallets. The proximity ofthe perforation pattern to the outside edge of the plenum chamber, theslack in the plenum chamber and the rigidity of the backing member allconstitute aspects of the pillowing control.

In U.S. Pat. No. 4,272,836 for an operative air pallet-type patientmover, pillowing is controlled by having the pattern of perforationsextending to the edge of the plenum chamber and the sides of the plenumchamber are purposely designed to match the head and torso of thepatient from the shoulders to the hip, where the load mass of thepatient is concentrated.

In U.S. Pat. No. 4,272,856, certain parameters with respect to the load,i.e., weight, patient size and load footprint, are matched to the plenumchamber area, otherwise the unit will not work or works poorly. Theco-applicant herein ascertained that an air pallet plenum chamber uponpressurization tends to take a shape resulting in lateral reduction ofthe plenum chamber air film footprint. Since the patient's body ismovable and flexes, this creates significant problems. Not only is suchload not rigid, but the top flexible sheet is not a rigid member and,indeed nothing structurally is rigid. Further, only the torso and headis supported by the plenum chamber. (i.e., jacked up), and the rest ofthe body (legs, arms. etc.) simply drag along with the air pallet oncean air bearing or air film is created by escape of air through theperforations within the thin, flexible bottom sheet. If the patient hasa broken limb, this is not a small problem, but a catastrophe.

Patient loading on the air pallet and removal from the air palletprovides significant problems, as well as the ability to create apatient mover having a size to fit the patient, the bed, the portablegurney and a procedure table such as an operating table.

These problems led initially to developments exemplified by U.S. Pat.Nos. 4,528,704 and 4,686,719. However, these developments raised morequestions than they provided answers. The key to solving most of theproblem areas seems to the applicants to lie in the utilization of arigid backing member, but a rigid backing member .[.make.]. .Iadd.makes.Iaddend.it more difficult to place the patient on the patient mover.The patient has to be physically log-rolled way over, and almost facedown to one side so that the rigid backing member is juxtapositioned tothe patient, and the patient is then rolled back over so that thepatient ends up supine on the patient mover. This procedure follows thatof placing the sheet under a patient when on a hospital bed, but then asheet can be folded in half and slid under the patient without turninghis body excessively to one side. Such is not so for a patient moverhaving a rigid backing member.

Attempts were made at formulating a useful air chamber type air palletusing a flexible pad to eliminate the rigid backing member by orsubstituting an all-flexible sheet material structure for such rigidbacking member, FIGS. 4 and 5 of U.S. Pat. No. 4,528,704 amounted to aninitial approach. Generally at the same time, the applicants consideredthe separation of the jacking action from that of creation of thefrictionless air film. This led to the development of stacked tubes, onefunctioning as a pure jacking chamber, and the second as a combinedjacking chamber and plenum chamber. The result is a gas pressurizedjacking structure with improved load stability, in which the samecompressed air pressurizing the upper chamber through a dynamicflowthrough arrangement, functions in passing through the pin holeperforations of the plenum chamber thin, flexible bottom sheet, tocreate the air film. Such dynamic air pallet is the subject of U.S. Pat.No. 4,417,639.

In air chamber-type air pallet patient movers as exemplified by FIGS. 4and 5 of U.S. Pat. No. 4,528,704, a phenomenon was experienced as theresult of air pressurization of the tubular chambers formed by sealedsections of the upper two thin flexible sheets and the airpressurization of the plenum chamber Underlying all of the upper row oftubes .[.common.]. .Iadd.commonly .Iaddend.to the intermediate thin,flexible sheet of said row of tubes. The entire unit took on a fullvertical circular cross-section and attempted to approach a cylinder asseen in applicants' FIG. 1, which was termed "hot dogging". Such hotdogging was found to lead to extreme air pallet instability, with anyload on the air pallet easily displaced. Applicants have determined thatthe pressurization of such air chamber-type air pallet is quite criticaland a careful balance is required between inflation and flotation.During hot dogging, the plenum chamber takes on an almost circularcross-section in a plane at right angles to the longitudinal axis of theseries of line joined tubes formed by the top thin, flexible sheet 202,the intermediate thin, flexible sheet 204 and the bottom thin, flexiblesheet 206 of air pallet 200 of the drawings. This structure conforms toFIG. 4 of U.S. Pat. No. 4,528,704. A plenum chamber 208 is formedbetween the thin, flexible, intermediate sheet 204 and bottom sheet 206and the sheet 206 has literally thousands of closely spaced pin holes210 through which air escapes from the plenum chamber to form an airfilm or air bearing A between the thin, flexible bottom sheet 206 andthe generally rigid, planar surface 212. Each of the transverse seallines 214 joining the top and intermediate sheets 202, 204, togetherforming individual compressed air pressurizable chambers or tubes 216,function as hinging areas between adjacent tubes. The result of such ishigh instability for any load such as a patient's feet in contact withthe exterior of the top thin, flexible sheet 202. It is further obviousthat the single large sectional area formed by the plenum chamber 208 iswithout a means for controlling hot dogging and is thus extremelysusceptible to the instability problem.

Further, in arriving at FIGS. 4 and 5 of U.S. Pat. No. 4,528,704,co-applicants hereof have attempted to form a useful air chamber-typeair pallet. Such is hampered by a phenomenon resulting both in aninstability problem and under severe conditions a loss or reduction ineffective plenum chamber air film or air bearing footprint print area tothe extent where the air bearing cross-sectional area becomes too smallto carry the load, the load may roll off the upper flexible sheetsupport area as the air pallet assumes a cylindrical shape and the airpallet may ground out as it loses air bearing cross-sectional area or acombination of all three adverse effects occur.

Where the plenum chamber P, FIG. 2, is of a given width W when flat anddeflated, the tendency of such plenum chamber is to have that width Wreduced to W the diameter of the tube when full inflated, as seen by acomparison with FIG. 3.

Another phenomenon which occurs utilizing the air chamber-type airpallets of FIGS. 4 and 5 of U.S. Pat. No. 4,528,704 is a lack ofrigidity of the air chamber assembly defined by the top thin, flexiblesheet 202 and the intermediate flexible sheet 204, as the result of airpressurization of all of the chambers 216 of the row of tubes and theair pressurization of the plenum chamber 208, which underlies the tubearray defined by thin, flexible sheets 202, 204. While the walls of theindividual chambers or tubes 216 are relatively taut, upon airpressurization of the same, whether in the sealed air pressure tubessuch as the embodiment of FIG. 4 of U.S. Pat. No. 4,528,704 or theflow-through tubes 80 of the FIG. 5 embodiment of that patent, the lineconnections between abutting sides of the parallel row tubes 216 permittube sectioning lines to act as hinges, and causing the unwanted hotdogging of the air pallet 200, FIG. 1. Further, .[.while.]. the presenceof a load such as a patient and the weight thereof, depressing the uppersurface of the air pallet FIG. 1 (corresponding to FIGS. 4 and 5 of U.S.Pat. No. 4,528,704) tends to resist the ballooning of the air pallet,and enhance the stability of the load. However, such structuresinherently lack means for preventing significant lateral shrinking ofthe plenum chamber.

In view of the lack of rigidity of the air chamber type air pallets asillustrated in FIGS. 4 and 5 of U.S. Pat. No. 4,528,704, aninvestigation by the applicants of the various causes for suppleness incontrast to desired rigidity (in view of the attempt to substitute anair chamber or air chambers for the rigid planar backing member of theair pallet) led to the determination that rigidity of any part of an airchamber type air pallet can be achieved from solely two means, (1)varying the air pressure within the various chambers of the air pallet(the result of which tends to create ballooning, and the high airpressure was found to be undesirable to the inherent ballooning ortendency to balloon), and (2) employing a solid unbendable stiff uppersheet supporting the load, and for a point load, spreading that loadover the complete surface of the unbendable upper sheet. While theunbendable upper sheet was sufficient to avoid ballooning, the desiredrigidity can only come from the air pressure within or flowing throughthe various chambers of the thin, flexible sheet structure.

Further, in operation of the air chamber type air pallets, FIGS. 4 and 5of U.S. Pat. No. 4,528,704, the plenum chamber being unsectionalized andlinked solely to the tubular arrays at opposite ends and along oppositesides of the air pallet, such structure either creates, or enhancessuppleness of the structure which prevents the row of tubes of the airpallet from acting as a substitute for the rigid backing member normallyemployed in such air pallet structures.

It is, therefore, a primary object of the present invention to providean improved air chamber type air pallet of the patient mover or patientpositioner type which is lightweight and which may take the form of a"soft pad" or "hard pad" type having the facility for the creation of asemi-rigid or generally rigid backing member, which eliminates the needfor the inclusion of a rigid or semi-rigid sheet as a load backingmember, which permits the patient to be physically moved in a relativelyfrictionless manner, which is formed wholly of thin flexible film orsheet material, which includes a degassing feature upon point pressureapplication to inherently induce therapy to the patient supported by thesame, which is highly stable in operation, which readily holds thepatient in a supine horizontal position, which tends to prevent spinalflexure, which may function as a body wrap to restrain the patientlaterally and vertically, and which may be readily folded andtransported upon depressurization of the air pressurized chambers formedby plural, locally sealed thin flexible sheets.

It is a further object of the present invention to provide improved,soft pad or hard pad, air chamber type air bearing patient movers whichmay be formed totally of thin flexible sheet material in multiple layerform with selective sealed pressurized air containment and/or flowthrough chambers by localized thermal bonded or sewn seal lines betweenrespective sheets of a stacked sheet array, which may selectivelyinclude portions of the soft pad or hard pad air pallet with controlledrigidification for support of the patient with assured comfort, whichfacilitates patient positioning, which correlates the air bearingfootprint to that of mass distribution of the load on the patient mover,which is particularly useful as a patient mover, which utilize a seriesof side-to-side linked hollow tubes subject to constant pressurized airapplication or continuous compressed air flow as single or pluralstacked arrays of side-to-side linked hollow tubes defining a semi-rigidbacking member for the air pallet, which air pressurization can bevaried or maintained below that which would induce patient capillaryclosure, which facilitates lubrication of the patient body surfaceduring support of the patient, which prevents lateral shrinkage of theportion of the compressed air plenum chamber forming the air filmthrough the bottom thin flexible sheet perforated portion to preventbottoming out of the load on the air pallet, which forms an air mattresswhich may be selectively rendered highly rigid as a "hard pad" or highlysupple as a "soft pad", depending upon need, without removal of thepatient therefrom, and which has application universally from use at theaccident scene, to emergency transport from the scene of the accident tothe hospital or other treatment facility, transport throughout thehospital including to and from the operating room, and as an airmattress with minimum trauma to the patient at all times.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view of an air pallet of the prior artshowing the effect of unwanted hot dogging under air pressurization of asingle row of linked tubes, and the single plenum chamber underlying thesame.

FIG. 2 is a sectional view of a single tube prior to air pressurizationthereof.

FIG. 3 is a sectional view of the tube of FIG. 2 illustrating lateralshrinkage thereof upon air pressurization.

FIG. 4 is a schematic vertical sectional view of an air chamber-typepatient mover air pallet formed of two thin, flexible sheets, forming apreferred embodiment of the present invention, prior to inflation.

FIG. 5 is a vertical sectional view of the air pallet of FIG. 4, underair pressurization.

FIG. 6 is an end view of the air pallet of FIGS. 4 and 5 duringplacement partially beneath the patient and under air pressurization.

FIG. 7 is a similar end view to that of FIG. 6 during initiation ofpatient transfer, partially supporting the patient.

FIG. .[.7.]. .Iadd.8 .Iaddend.is a further end view, similar to that ofFIGS. 6 and 7, with the patient fully supported by the air pallet.

FIG. 9 is a schematic, vertical sectional view, illustrating theanti-shrink effect resulting from the utilization of small diameterside-to-side linked tubes of the two flexible sheet air chamber-typepatient mover air pallet of FIGS. 4 and 5.

FIG. 10 is a schematic top plan view of a two-sheet air chamber-typepatient mover air pallet, forming a further embodiment of the invention.

FIG. 11 is a schematic top plan view of yet another embodiment of thetwo-sheet, air chamber-type patient mover air pallet of this invention.

FIG. 12 is a schematic top plan view of a further embodiment of theinvention for a simplified air chamber-type patient mover air palletformed of a series of longitudinally spaced tubular air chambers ofvarying diameter.

FIG. 13 is a schematic top plan view of a further embodiment of atwo-sheet air chamber-type patient mover air pallet of the presentinvention.

FIG. 14 is a schematic top plan view of a simple two-sheet flexible filmair chamber-type patient mover air pallet forming yet another embodimentof the present invention.

FIG. 15 is a schematic representation, in sectional form, of a singlechamber air pallet contrasted to that formed by a series of linked tubesand illustrating the significant increase in tangential air filmfootprint for the air pallet formed of a series of small diameterside-to-side linked tubes, to that of the single chamber-type airpallet.

FIG. 16 is an X-Y coordinate plot of the operating parameters associatedwith the air chamber-type patient mover air pallets forming variousembodiments of the present invention.

FIG. 17 is a schematic top plan view of a further two-sheet flexiblefilm air chamber-type patient mover air pallet of the present invention.

FIG. 18 is a schematic top plan view of a modified form of airchamber-type patient mover air pallet of the present invention.

FIG. 19 is a schematic vertical sectional view of a modified form,simple two-sheet flexible film air chamber-type patient mover air palletof the present invention prior to air pressurization of the tubularchambers thereof.

FIG. 20 is a schematic vertical sectional view of the air pallet of FIG.19 under air pressurization, taking a "cradle" position about a patientthereon and conforming to a chute supporting the air pallet and betweenwhich an air film is developed.

FIG. 21 is a schematic vertical sectional view, on an enlarged scale, ofthe air pallet of FIG. 4. illustrating the effect of the load and thepreferred placement of the pin hole perforations within the thin,flexible bottom sheet of that structure.

FIG. 22 is a similar view to that of FIG. 21, illustrating theflattening of the tangential contact portion of the tubes with theunderlying support surface and the resultant air bearing createdthereby.

FIG. 23 is a schematic vertical sectional view of a flexible film airchamber-type patient mover air pallet, forming yet another embodiment ofthe present invention.

FIG. 24 is a schematic vertical sectional view of an alternate form ofthree-sheet, air chamber type patient mover air pallet of the presentinvention.

FIG. 25 is a schematic vertical sectional view of yet a furtherembodiment of the invention in the form of a three-sheet, flexible filmair chamber-type patient mover air pallet with an air reservoir featurefor preventing complete, collapse of any one of the segmental plenumchambers incorporated therein.

FIG. 26 is a top plan view of a four-sheet, flexible film airchamber-type patient mover air pallet forming a preferred embodiment ofthe present invention.

FIG. 27 is a top plan view of the top, thin, flexible sheet of the airpallet of FIG. 26.

FIG. 28 is a top plan view of the first intermediate, thin flexiblesheet of the air pallet of FIG. 26.

FIG. 29 is a top plan view of the second intermediate, thin flexiblesheet of the air pallet of FIG. 26.

FIG. 30 is a top plan view of the bottom, thin flexible sheet of the airpallet of FIG. 26.

FIG. 31 is a schematic, vertical sectional view of the assembly of thefour sheets for the air pallet of FIG. 26 and the longitudinal seallines selectively joining the same to form air tubes or air chambers inmultiple linked tube and linked row fashion for the air pallet of FIG.26.

FIG. 32 is a perspective view, partially cut away, of the air pallet ofFIG. 26 after inflation, and illustrating in dotted lines a fifth, thin,flexible sheet to form a second air bearing at the top of the airpallet.

FIG. 32a is a perspective view, partially cut away, of the air pallet ofFIG. 32, modified to form a flow through single air source type airpallet.

FIG. 33 is a top plan view of a four-sheet, thin flexible film, airchamber-type patient mover air pallet forming yet a further embodimentof the present invention.

FIG. 34 is a top plan view of a first intermediate, thin, flexible sheetof the air pallet of FIG. 33.

FIG. 35 is a top plan view of one of dual second intermediate, thinflexible sheets of the air pallet of FIG. 33.

FIG. 36 is a top plan view of a bottom thin, flexible sheet of the airpallet of FIG. 33.

FIG. 37 is a schematic, vertical sectional view of the air pallet ofFIG. 33, illustrating the longitudinal seal line between the thin,flexible sheets of that air pallet, and the formation of individual airtubes or chambers thereof.

FIG. 38 is a perspective view, partially broken away, of the air palletof FIG. 33 under air pressurization and illustrating the extent of hotdogging of that air pallet.

FIG. 39 is a schematic, vertical sectional view of a modified airchamber-type patient mover air pallet of FIG. 26, forming yet a furtherembodiment of the invention.

FIG. 40 is a plan view of an open frame forming a lateral anti-shrinkelement employable in the alternative to the rigid sheet of theembodiment of FIG. 39.

FIG. 41 is a schematic, vertical sectional view of yet a furtherflexible sheet air chamber-type patient mover air pallet of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention in the various embodiments described in detailhereinafter takes into account the parameters discussed within theBackground Of The Invention section of this specification, and from theneed to provide effective air chamber-type air pallet patient moverspermitting the loading of the patient thereon and the unloading of thatpatient therefrom without the trauma and discomfort caused by theattendent log rolling of the patient to accomplish those actions. Theflexible backing chamber air pallet involves, in addition to jacking,pillowing and ballooning other critical phenomenon and operatingparameters which must be controlled. The air pallets of the inventionadditionally require means for preventing the hot dogging phenomenondiscussed above. The applicants have determined that the existence ofsingular or multiple large sectional areas which cause a major portionor the totality of the air pallet, with the singular chamber or multiplelinked chambers inflated, to take a true circular cross-sectionalconfiguration results in instability to the load and trauma to thepatient. Keyed to the field of patient transfer, the present inventionin the several embodiments as set forth hereinafter, provides a solutionto the problem of placement of a patient onto an air chamber-type airpallet patient mover, which eliminates undesirable log rolling, andpossibility of severe spinal cord injury to the patient.

Referring to FIGS. 4 and 5, one embodiment of an air chamber-typepatient mover air pallet 310 is formed of two thin, flexible sheets 302and 304 which are sewn together about all four edges or heat sealed viaspaced longitudinally extending seal lines 308 to form individualside-by-side parallel chambers 306. The individual chambers or tubes 306which tend as per FIG. 5 to take a circular cross-section when airpressurized via a source of compressed air indicated by arrow 314applied to the chambers, are, in this case for example, connected inseries through an air inlet tube 312. To create an air bearing A beneaththe bottom thin flexible sheet 304 thousands of pin hole-typeperforations 316 are provided within the bottom sheet 304, in this casepreferably limited to the central area of respective tubes or chambers306. The .[.two-piece.]. .Iadd.two-ply .Iaddend.patient mover air palletconsists, therefore, of an imperforate upper, thin flexible sheet 302attached at intervals to a lower, thin flexible sheet 304 with aplurality of perforations 316 within the bottom thin, flexible sheet andan air inlet tube 312 communicating to all chambers or tubes 306. Thepatient P is moved onto the patient mover air pallet by folding the airpallet 310 about its longitudinal center line, FIG. 6 defined in thiscase by the middle longitudinal seal line 308, prior to airpressurization of chambers 306 with the patient lying in the supineposition. By wedging the folded two-piece air pallet with theperforations 316 facing each other, the folded, deflated patient moverair pallet 310 can be placed under the patient much in the same mannerthat a folded sheet can be placed under a patient when remaking the bedwithout moving the patient from the hospital bed. Such may beaccomplished with relatively little movement of the patient.

Upon air pressurization of plenum chambers 306, the patient is jacked tosome extent, an air bearing is created at A, FIG. 6, between the foldedover halves of the patient mover air pallet 310, and the patient P iscaused to move up onto the imperforate upper thin, flexible sheet 302,FIGS. 6, 7. The patient can then be moved back onto a gurney, backboardB or the like, with or without environmental control sheets, FIGS. 7, 8as support equipment, and as needed or desired.

By gently inflating the patient mover air pallet 310, it may be pulledby one transverse edge across itself with frictionless movementresulting from the application of pressurized air to the interior of thechambers or tubes 306 which function as plenum chambers. The air bearingA is created as a result of compressed air discharging from the plenumchamber through the pin hole perforations 316 which open unrestrictedlyinteriorly and exteriorly of the patient mover air pallet 310. At thesame time by jacking, the patient's body is lifted evenly. The airpallet 310 includes means for controlling pillowing of the air palletplenum chambers formed by the linked tubes, and the patient iseventually totally supported by the patient mover air pallet. Thepatient may then travel across an environmentally controlled sheet ontobackboard B.

Referring next to FIG. 9, and comparing that figure to the result ofinflation of a flat, deflated single chamber body, FIGS. 2 and 3, theapplicants have ascertained one of the operating parameters and keyaspects of the patient mover air pallets of the present invention. Wherethe desired lateral width W, FIG. 2, of an air pallet is to bemaintained, the air chamber pallet is composed of or built up of manysmaller diameter sectional membranes linked together resulting in asignificant reduction in lateral width, or shrinkage. Width W", afterair pressurization of chambers 306 of the patient mover air pallet 310of FIG. 4, is significantly larger than the width W'of the singleinflated chamber 220, FIG. 3, whose diameter D when fully inflated isapproximately two-thirds of its flat, deflated width W, FIG. 2. Notethat the diameter D' of each chamber 306 in FIG. 9 is significantlysmaller than the diameter D of the single chamber 220 structure wheninflated. FIG. 3.

In terms of desired flow paths for compressed air under pressure movingthrough the various tubes or tube sections of a two-ply air palletformed solely of two thin, flexible sheet material heat sealed inlocalized, linear fashion, FIGS. 10, 11 and 12 are exemplary of seallines forming parallel flow paths from a single air inlet. In FIG. 10air pallet 410 has compressed air source 414 feeding air via air inlet412 to parallel tube plenum chambers or sections 416, each linked byflow reverse turns 420 defined by seal lines 408.

In FIG. 11 a singular flow path 520 starting from the inlet 512, ofmodified spiral form by seal lines 508 between two flexible sheets formsa unitary plenum chamber air pallet 510. In FIG. 12, the two sheet airpallet 610 uses a plurality of short length parallel unevenly spacedseal lines 608 transverse to the longitudinal extent of the air pallet610, permits parallel flow paths to open from right angle flows alongopposite longitudinal edges of the air pallet which longitudinal pathsform air flow manifolds 622 from inlet 612 from air source 614. Thetubes or plenum chambers 616 which run transversely, and are of varyingwidth, meet the specific mass concentration areas of the load supportedthereby (human body).

FIGS. 13 and 14 show additional embodiments of the present invention,specifically directed to two-sheet air chamber-type patient mover airpallets, as at 710 and 810 respectively. In FIG. 13, compressed air, asindicated by arrow 714, enters inlet 712 for parallel flow throughspiral-like dual plenum chambers to laterally opposite sides of the airpallet 710 as defined by seal lines 708 constituted by vertical andhorizontal ribbing of the chambers defined thereby. The distance betweenparallel longitudinally extending ribbing, i.e., seal lines, can bealtered, graded, enlarged, or decreased to control lift, load support,cradling, etc. of the patient to meet the environment needs for thepatient mover air pallet.

It is apparent that by creating a number of small diameter chambers ortubes in a single linked row in accordance with the superpositioning ofair pallet 310, FIG. 4, on a large circle C to form a chamber 220equivalent to that of FIG. 3, D' is many times smaller than the originalD associated with chamber 220. The hot dogging of the resultingstructure is considerably reduced and provides effective control insupporting a load thereon, particularly a patient P. Upon closeexamination, the applicants have determined another change which takesplace to the bearing surface of a cylindrically-shaped object such as aplenum chamber bearing on the underlying fixed support surface such assurface 311 where that object is formed of a thin, flexible sheet. Evenwithout loading, the large circle C assumed to be the cross-section ofan elongated tube, air pressurized and formed of thin, flexible sheet,will have an appropriate footprint when flattened against the underlyingfixed support surface 311 spreading from its contact point of tangencyat the center of the circle C. In FIG. 15, the large circle C footprintoccupies a width or dimension X which is significantly smaller than thepotential tangential air film footprint X', as represented by the sameextreme tangential contact point for the outermost small diameter D'tubes of the patient mover air pallet 310 superimposed on the largecircle C, FIG. 15. By dividing the circular circumference so as to forma multiplicity of smaller circles of a diameter D'as exemplified by thefirst embodiment of the present invention, FIG. 4, i.e., patient moverair pallet 310, the combined circumference of the smaller tubes stillhas the same circumference as the big circle C, but the potentialfootprint area of the load can be significantly larger. The applicantshave ascertained that not only is there control of the hot doggingtendency of such air chamber-type patient mover air pallets, but thepresent invention maximizes the load footprint area and indirectly theperforation area of the individual plenum chambers defined by theseparate tubes or chambers 306, providing the air film or air bearing A.The control is therefore of the shrink of the load footprint area incontact with the supporting surface of the plenum chamber or chambers,which in turn provides the ability of the air pallet to support the loadP. In addition, FIG. 15 represents a further phenomenon or operatingparameter ascertained by the applicants. Instead of the large volumetricarea of the lower half of the circle C (beneath the superimposed airpallet 310) consisting of laterally edge-abutting tubes or chambers 306,such is minimized (essentially eliminated), the result of which isstabilization of the air pallet against hot dogging. Additionally, aswill be seen hereinafter, the individual tubes 306, due to the presenceof the load P and on the basis that the chambers or tubes 306 constituteplenum chambers through which air escapes via pin holes 316 to form theair bearing or air film A between the thin, flexible bottom sheetportions of the plenum chambers bearing the perforations, flatten toform small footprint areas corresponding to the large circle C footprintX of FIG. 15. The tubes 306 perform the necessary pillowing control andanti-ballooning. The applicants have additionally determined that bylimiting the area of the thousands of pin hole-type perforations to thatsurface area of each plenum chamber or tube 306 which is flat and innear contact with the planar rigid support surface 311, essentially onlythe flat surface area having perforations 316, the footprint of the airfilm for the patient mover air pallet 310 conforms to that of the loadP.

FIG. 16 is a rendition of an X-Y coordinate structure and depiction ofwhat occurs in FIG. 15, evidencing the operating parameters of a single,very large plenum chamber C in contrast to an air pallet formed ofmultiple linked tubes of two-sheet form constituting plenum chambers andfunctioning to jack the load, support that load, and to produce theunderlying air film A, FIG. 5. The plenum chamber air film extends alongthe X axis of the plot, with the plot illustrating vertically upwardfrom that X axis, in respective order of magnitude, jacking, pillowing,ballooning and hot dogging control factors or parameters of the airchamber-type patient mover air pallets of the present invention. As onephenomenon reduces, one or more increase. The applicants structures ofthe present invention control the changes to maximize the air filmfootprint with the air chamber or chambers preferably taking the form ofelongated cross-sectional rectangles rather than being of elongated hotdog shape, i.e., circle C, FIG. 15.

The aspects discussed above, particularly with respect to FIGS. 15 and16 are keyed to the necessity for reduction in lateral shrink andmaximum retention of the air film surface with minimal loss of the airbearing A developed between the thin, flexible bottom sheet of the airpallet and the underlying rigid planar support surface 311.

In that respect, it is apparent that shrink does not occur along theaxis of a tubular membrane, but perpendicular to that axis.Mathematically shrink measures out to be about one-third or a functionof π. From FIGS. 10-14 the control of the lateral shrink, parallel tothe developed air film A and its structural orientation with respect tothe position of the load on an air pallet is the key to the air pallet'sperformance. An air pallet formed of two thin, flexible sheets locallyheat sealed to each other for movement of a supine body permits thebasic unit to have a series of tubes running in the same direction,parallel to the fold line. The size of the tube diameter determines theheight of the inflated unit and is preferably kept to a relatively smallvalue. By using a combination of tubes, some perpendicular to others,control of shrink occurs in both directions, and such tube arrangementperforms an anti-shrink action.

FIG. 17 illustrates schematically, a two-sheet air pallet similar tothat shown in FIG. 4, using like numerals for like elements, with tubes306 forming plenum chambers defined by seal lines 308, all beingparallel and in line with flow entering inlet 312 from a compressed airsource 314 flowing transversely across the air pallet 310 to the sideopposite the inlet 312 and with parallel air flows through theindividual tubes 306 of the tube array.

FIG. 18 illustrates an air chamber-type patient mover air pallet 910 ofsimple two flexible sheet form with a single air inlet 912 receivingcompressed air from source 914 and with flow occurring within tubes 906along opposite longitudinal sides, while tubes 922 extend transverselyparallel to each other, from one longitudinal end to the other, betweenlongitudinally extending tubes 906 to opposite sides thereof, allreceiving compressed air from a single source 914. In all of theembodiments of the invention using two thin flexible sheets, themultiple tubes constitute plenum chambers described above and the thinflexible bottom sheet, in each instance includes a pattern of thousandsof closely spaced pin hole perforations which are not shown forsimplification of the views.

Variations occur by separation of flows into multiple chambers ofserpentine or spiral form to prevent the multiple thin, flexible sheetstructure from reaching its free cylindrical shape in contrast to thatof a singular tubular unit.

Thus, various combinations of fabrication and joining of two sheets ofsimple two-sheet air chamber-type patient mover air pallets may beemployed, accomplishing different end results, but all based on thebasic principles discussed in the creation of the air pallet 310, FIG.4.

Reference to FIGS. 19 and 20 show a modification of the basic two-sheetair pallet 310 of FIG. 4. In this case, the air pallet 310' otherwisecorresponding to that of FIG. 4 is again formed of a thin flexible topsheet 302' and a thin, flexible bottom sheet 304' being heat sealed orotherwise bonded or sewn along four sides and longitudinal lines 308' toform individual tubes or chambers 306'. However, the lateral distancebetween lines 308' of attachment for the lower sheet 304' is much largerthan that for the upper sheet 302' so that upon inflation, the airpallet 310' tends to curl upwardly into a U-shaped form, see FIG. 20,and thus cradle a patient P. With air pressurization of the individualplenum chambers 306' the inverted arch tends to adversely alter the airbearing A created between the thin, flexible bottom sheet 304' and theunderlying rigid planar support surface 311' as air exits from pin holes316'.

A U-shaped chute 311'a, shown in dotted lines maintains the air bearingor air film A if curved corresponding to the inverted arch, FIG. 20. If,as shown, the lower sheet has excess material accumulated between thejoined lines compared to the upper sheet, then upon inflation of thechambers a "cradling" phenomenon takes place. To the contrary, if moreslack is accumulated between the upper sheet seal lines then the airpallet will arch upwardly.

As touched on briefly above, turning to FIG. 21, where the simpletwo-sheet air chamber-type patient mover air pallet 310 takes the formof plenum chamber tubes 306 which are joined by longitudinal seal lines308 and under air pressurization, the placement of the load (patient) Pon the air pallet causes a flattening to occur to the circularcross-section tubes, both at the top and at the bottom. Where thecylindrical tubular members face the underlying fixed support surface311, each will tend to flatten out over a limited surface area of thecircular arc. Depending upon the weight of the load P and the relativeair pressure inside the tubes, the extent of flattening will vary. Thegreater the surface area of the thin, flexible bottom sheet in nearcontact with the underlying support surface, the greater the lift andarea for air film development through the perforations 316 facing theunderlying support surface and the greater the tendency of the airpallet to function at a lower operating air pressure. Additionally, asper FIG. 22, there is less longitudinal channel voids V to allow the airto escape along the axis for the tubular joints defined by the seallines 308 without providing any lift or developed air film A. Applicantshave determined that by limiting the area of perforations to that areanormally flattened within the thin, flexible bottom sheet 304, as at 318for each of the tubes or plenum chambers 306 the effective footprint ofthe developed air bearing or air film A remains substantially equal tothat of the footprint of the load P (patient) supported by the airpallet 310. Applicants have determined that by using a great number ofsmall diameter pin hole-type perforations, i.e., literally thousands ofperforations, there is more effective lift from the escaping air throughthe perforations 316. To obtain maximum lift, using minimum air pressureit is desirable to have as large a tangential flat area as possible foreach of the tubes 306 along the fixed planar support surface 311, toobtain maximum lift. If the perforated area is limited to the flat areafor each of the tubes 306, then the effective surface area of thedeveloped air film, i.e., the footprint of the air film is maintainedapproximately equal to that of the load P.

From the discussion above and as it relates to the embodiments of theinvention described in detail above, and those described hereinafter, itis obvious that a large singular tubular structure is not an effectiveway to either jack a load, or maintain an air film large enough to movethe load while providing stabilization of the load riding on an airpallet particularly one of the air chamber-type. By utilizing a seriesof small diameter tubes as a lateral array with those tubes functioningas plenum chambers, by restricting the supporting surface of the plenumchamber which is flattened in contact with the underlying relativelyfixed planar support surface, and by limiting the area of perforationsto such area, maximum lift is achieved and maximum film lubrication areafor the load thereby resulting in the largest overall efficiency for anair pallet operating under the least volume and pressure of air input tothat plenum chamber for jacking the load, for controlling pillowing forcreation of the air bearing and for stabilization of the load, withrestricted air loss between the plenum chambers creating the developedair film.

An important operating parameter which is critical to successfuloperation of air chamber-type patient mover air pallets (and to such airpallets employed generally in material handling) involves the rigidityof the structure handling the patient or other load. Rigidity can onlybe achieved from two means as discussed previously: the air pressurethat develops pillowing and which leads to ballooning and the weight ofthe load itself.

The present invention also resides in the appreciation that rigiditymust come from the pressurized air filling or flowing into and through aflexible multiple tube structure and is accomplished by chambering ortubular configurations which are formed of or include means whichprovide lateral rigidity and additionally resist the downward forcecreated by the load on the top of the air pallet. Due to the possibilityof induced trauma to the patient during patient moving, these needs mustbe accomplished while avoiding point contact between the patient and arigid surface, the result of developed bending moment while utilizingassemblies that form semi-rigid or near rigid members when airpressurized.

The development of operable two-sheet, soft air chamber-type patientmover air pallets in the form shown in FIG. 4 and in accordance withvariations thereof, through FIG. 22 have led to successful creation ofsuch air pallets utilizing the two thin, flexible sheets to form asingle row of chambers or tubes which are physically linked or joined,and which include means defined by a third sheet or its equivalent toform semi-rigid backing chambers as the equivalent for the rigid sheetor semi-rigid sheet of the earlier air pallets discussed in theBackground Of The Invention portion of this specification. In FIG. 23,an air chamber-type patient mover air pallet, indicated generally at1010 is formed of a thin, flexible upper or top sheet 1002 physicallyseparate from a thin, flexible bottom sheet 1004, but linked by verticalimperforate stringers 1022 which are sealed or otherwise joined atopposite ends by seal lines 1008 to sheets 1002, 1004 to thereby definelinked plenum chambers or plenum chamber sections 1006 open to eachother at the ends or otherwise. Sheet 1004 has perforations 1016 throughwhich compressed air from source 1014 after entering the plenum chambersthrough the plenum chamber 1006 to the extreme right and by flowingtherebetween seeks escape through the pin hole-type perforations 1016 toform air bearing or air film A between the bottom thin, flexible sheet1004 and the generally fixed underlying support planar surface 1011.Stringers 1022 form vertical walls which are equally pressured onopposite sides to render those stringers or walls 1022 taut as theresult of air pressurization. Such stringers or walls 1022 are requiredat laterally spaced locations across the full width of the plenumchamber or at least the area of perforations forming the underlying airbearing A. Contrary to the embodiment of FIG. 4, not only is the airpallet formed of additional members other than the top thin, flexiblesheet and the bottom thin, flexible sheet, but the junctures between thesheets do not form "hinges" as occurs for seal lines 308 joining the topand bottom sheets 302, 304 of the embodiment of 310, FIG. 4. To thecontrary, by utilizing stringers or vertical walls .[.102.]. .Iadd.1022.Iaddend.which are subject to air pressurization on opposite sides, suchmembers as a result of inflation function as a "I" beams. The same hasbeen found true where air pallets of the air chamber-type are formedwhere the defined chambers are commonly not plenum chambers throughwhich air escapes via the pin hole perforations 1016 to define the airbearing A, but are jacking chambers for jacking the load and constitutean array above the plenum chamber and separate therefrom. The presentinvention is therefore to a significant extent directed to airchamber-type air pallets, where multiple tubes or chambers are formed ofthe thin, flexible sheet material, with the tubes being joined at twopoints which are some degrees apart on the circumferences of the tubes.

The applicants have determined that when two tubes are attached at asingle point (a line over their length) and then inflated they readilybend around the point of attachment with that point of attachment, orline of attachment acting as a linear hinge. To the contrary, tubeswhich are attached at two points, particularly in the order of 90° aparton their circumference, when inflated, will form a rigid member betweenthe attachment area, i.e., a common wall which resists hinging and whichfunctions as an I-beam.

In accordance with the embodiment of FIG. 23, which in all otherrespects is similar to the embodiment of FIG. 4, where many tubes arefastened side-by-side over an extended width, a rigid air platform iscreated by the tubes constituting plenum chambers and developing the airfilm A. Similarly, tubes fastened side-to-side over a circumferentialextent of a number of degrees will support a load and jack the load,irrespective of whether they are functioning as plenum chambers bearingperforations to create the underlying air bearing or merely air backingchambers.

Turning next to FIG. 24, a further embodiment of the invention isindicated generally at 1110. In this embodiment, which again is avariation of the embodiment of FIG. 4, the air pallet 1110 is formed ofthree separate, thin, flexible sheets, a thin, flexible top sheet 1102,a thin, flexible bottom sheet 1104 bearing areas of pin hole typeperforations 1116 which are closely spaced and in accordance with theprior embodiments, and a thin, flexible intermediate sheet 1122. Theintermediate sheet bears a number of holes or air passage ports 1124,permitting the air to move from chamber to chamber. The thin, flexiblebottom sheet 1104 is heat sealed transversely only at opposite sideedges, as at 1126, to the top sheet 1102. The interposed intermediatesheet 1122 is heat sealed along longitudinal lines as at 1128,alternately to the top and bottom sheets. Thereby, the top thin,flexible sheet 1102 and the intermediate thin, flexible sheet 1122 forman upper row of tubular chambers 1130, which alternate with and arelaterally offset from a lower row of tubular chambers 1132 formed byheat sealing intermediate thin, flexible sheet 1122 and bottom sheet1104. The upper row chambers 1130 are backing chambers or jackingchambers since they function to jack the load and act similar to thegenerally rigid backing member of U.S. Pat. No. 3,948,344 to support theload, and the lower row chambers 1132 are plenum chambers with the thin,flexible bottom sheet being perforated at 1116 for the three adjacentlower row chambers 1132 underlying the load P. In the basic structureshown in FIG. 24 an air inlet tube 1112 receives compressed air from asource indicated by the arrow 1114 with this air first passing throughone of the upper row chambers 1130 and then entering the laterallyadjacent lower row chamber 1132, in alternating sequence rendering aportion of the thin, flexible intermediate sheet 1122 rigid, i.e., likean I-beam. As a result, these tubes do not take a circular or ovalconfiguration, but, rather, a triangular cross-sectional configuration.As will be seen, the lines of attachment for the thin, flexible bottomsheet with respect to the upper row of chambers 1130 are at spacedtransverse positions defined by seal lines 1128, uniformly over thetransverse width of the plenum chamber, providing the desired rigidityto the structure while simultaneously limiting the lateral shrinkage ofthe developed air film A relative to the footprint of the load P(patient). Additionally, the air pallet of FIG. 24, due to the lateraloffsetting of the tubular chambers 1130, 1132, insures, thatirrespective of deflation of any one of these chambers for either thetop row or bottom row, the patient P will not ground out against theunderlying generally rigid planar support surface 1111. Thus, no pointcontact occurs between the patient with resulting trauma and thetendency to create bed sores. Additionally, the upper row of chambers1130 which do not function as plenum chambers, constitute a row of thin,flexible sheet material backing chambers of generally rigid form as asubstitute for the rigid backing member employed in a significant numberof air pallets developed by one or more of the applicants herein, bothin the area of material moving and more specifically the patient moverfield.

Referring next to FIG. 25, an air pallet 1210 is illustrated assupporting a load P as a further modification of the basic airchamber-type patient mover air pallet formed by three thin, flexiblesheets, an upper or top thin, flexible sheet 1202, a bottom thin,flexible sheet 1204 and an intermediate thin, flexible sheet 1222. Theupper and intermediate sheets form backing chambers 1230. Theintermediate thin, flexible sheet 1222 and the bottom thin, flexiblesheet 1204 form a series of separate plenum chambers 1236 when airpressurized from a source of compressed air as at 1214 entering inlettube 1212 to one of the upper chambers 1230. Suitable ports are providedas indicated at 1234 for communicating the chambers and permitting airflow to pressurize the upper row chambers and to enter the plenumchambers of the lower row, pressurize the same, and exit through thethousands of pin hole-like perforations 1216 within the thin, flexiblebottom sheet 1204. An air film A is developed between the bottom thin,flexible sheet 1204 and the generally rigid support surface 1211underlying the air pallet.

There are two aspects to this embodiment which are important. First, itis seen that the thin flexible bottom sheet 1204 and the thin, flexibletop sheet 1202 are jointed commonly to the thin, flexible intermediatesheet 1222 at uniform locations transversely across its width, as byseal lines 1238. Secondly, there is sufficient slack within the thin,flexible bottom sheet 1204 to provide plenum chambers 1236 of sufficientvolume or reservoir of air to insure adequate pressurization for thepassage of the air pallet over irregular surfaces or narrow voidswithout bottoming, while providing an antishrink construction via thecommon walls of the upper row of chambers 1230. It is noted that some ofthe ports 1234 extend through the common vertical walls joining adjacentupper row backing chambers 1230. The slack constitutes additionally thepillowing means for controlling the jacking, along with the thin,flexible sheet material defining the upper row of chambers whichfunction to jack the load and to form the equivalent of a rigid backingmember, i.e., a series of backing chambers 1230.

Referring to FIGS. 26 through 38 inclusive, a further embodiment ofconstant pressure sealed chamber, hard pad air pallet, indicatedgenerally at 10 is shown, being utilized, preferably as a patient mover.It is formed by superpositioning four thin flexible sheets of plasticfilm or a woven plastic impregnated fabric material of rectangular formin a stacked array, and thermal bonding the sheets together about thelateral edges thereof with the exception of at least one air inputopening between the third and fourth sheets to permit air pressurizationof a plenum chamber defined by the third and fourth sheets of thestacked array. The top or first thin flexible sheet indicated generallyat 12 overlies in order, a second sheet indicated generally at 14, athird sheet indicated generally at 16, and a fourth, bottom sheetindicated generally at 18. As evidenced in FIG. 31, which is a schematicrepresentation in which the sheets are vertically separated from eachother, the dotted vertical lines denote seal lines in which the thinflexible sheets 12, 14, 16 and 18 are locally sealed to each other alongelongated parallel lines extending from one, foot end 20 of the airpallet 10 to the other, head end 22, FIG. 26. Sheets 12, 14, 16 and 18of rectangular plan configuration are all of the same length but onlysheets 12.[...]..Iadd., .Iaddend.16 and 18 are of the same width.Intermediate sheet 14 may be somewhat narrower for purposes which willbe apparent hereinafter. In creating the assembly, the purpose ofstacking is to form individual sealed chambers or tubes which extendlongitudinally from one end 20 towards the other 22. The bottom sheet 18includes a rectangular perforated area indicated generally at 24 beinglocated within the center of bottom sheet 18, inwardly from both endsand from opposite sides, formed of literally thousands of closelyspaced, small diameter holes or perforations 26 of near pin hole size.The perforations 26 are similar to those of U.S. Pat. No. 4,528,704.Since the air pallet 10 may be employed in a hospital environment, anursing home or resident home, it may be of a woven nylon fabric such asa 70×100 denier 3.0 ounce square yard waterproof, vapor-permeable nylontwill. One side may be coated with ZEPEL® waterproof coating by DuPontand an appropriate anti-static agent. The other side may be coated withapproximately 11/4 ounce/square yard breathable tapable urethane and asuitable bacteria stat agent. Of course, the nature of the thin flexiblesheet material making up the air pallet 10 as well as the otherembodiments of the invention herein may vary depending upon theenvironment of use and the need for a special function or characteristicproperty for a given sheet or sheets making up the specific air palletin question as well as the nature of forming seal lines between sheets.

Line sealing between respective sheets 12, 14, 16 and 18 may be effectedby conventional thermal bonding techniques using linear heat application(under appropriate backing) on respective sides of the multilayerflexible sheet array. For the embodiment of FIGS. 26-32, line sealingoccurs along laterally spaced longitudinal seal lines 28, longitudinallyinwardly of both air pallet ends 20, 22, between sheets 16 and 18 inaccordance with the pattern shown in FIG. 29.

Next, a second, intermediate sheet 14 which is of shorter width thanthat of sheets 16 or 18 is placed on sheet 16. Further, linear thermalbond areas are effected to form seal lines 30 as per FIGS. 27 and 31 atpositions laterally offset from the thermal bond seal lines 28 betweensheets 16 and 18. Two of the thermal bond seal lines are immediatelyadjacent to the lateral edges 14a of thin flexible sheet 14. The lastset of longitudinally extending thermal bond seal lines 28 are effectedin accordance with the pattern shown in FIG. 27 initiating from topsheet 12, evenly spaced laterally from each other and including seallines adjacent opposite lateral edges 12a of that top sheet. Thermalbond longitudinal seal lines 32 are formed by and between top sheet 12,the second intermediate sheet 16 and bottom sheet 18 at lateral edges ofthe air pallet 10. Inwardly of the edges, seal lines 32 are effected atspaced lateral positions between sheets 12 and 14; laterally offset fromseal lines 30 between sheets 14, 16. Transverse thermal bond seal lines34 are required at both ends 20 and 22 of the air pallet 10 through allfour sheets 12, 14, 16 and 18. In some respects, the embodiment of theinvention of FIGS. 26 through 32 inclusive relates to the air pallet ofFIG. 4 of U.S. Pat. No. 4,528,704. In that respect, the top sheet 12 isprovided with .[.a.]. .Iadd.an .Iaddend.input or intake valve indicatedgenerally at 36, FIG. 26, which may be a normally closed flap type airintake valve conventional to this art. Such valve is shown schematicallyat 36 in FIG. 26 and FIG. 31. In order to effect a constant pressure,compressed air pressurization of the tubes, upper section 40 of airpallet 10 defined by sheets 12, 14, 16, in contrast to the lower section42 formed by the plenum chamber 68, sheets 16 and 18, the compressed airmay freely circulate to, between and through transverse channels at theends of seal lines 32 between sheets 12 and 14. Two rows of holes 38 areprovided within the first intermediate sheet 14, near respectiveopposite ends of the sheet, spaced between respective longitudinal seallines 30 for sheets 14, 16 so that air pressurization at constantpressure may be effected for the chambers or tubes created by sheets 14and 16 and the longitudinal seal lines 30 therebetween. The effect ofparticular longitudinal seal lines 30, 32 is to create an upper row ofsealed chambers or tubes from left to right at 44, 46, 48, 50, 52 and 54respectively, which are laterally offset from integrated, second rowchambers or tubes 56, 58, 60, 62 and 64 defined by seal lines 30 sealingsheets 14, 16.

Upon air inflation, as seen in FIG. 32, by the lateral offsetting of thetubes of adjacent rows of tubes by the intermediate spacing of seallines 30 and 32 between respective sheets 14, 16 and 12, 14, a series ofcommon walls rendered rigid upon air pressurization of the chambersresult in the creation of a semi-rigid backing member 66. For air pallet10 formed by the two rows of integrated tubes, the offsetting of thelower row of tubes or chambers from that of the upper row and the use ofcommon walls formed by the same sheet for an upper row tube and lowerrow tube constitutes both a means for reducing lateral shrinkage of theplenum chamber portion bearing the perforations 26 creating the airbearing A and a means for rigidifying the air pallet. It is theperforated area 24 defined by perforations 26 which creates thefootprint of the air bearing or film A, which must be correlated to thefootprint of the load formed by the mass of patient P supported by thetop thin flexible sheet 12. Air under pressure, as from a sourceindicated schematically by arrow 70, FIG. 32 is applied to the air inputor air inlet valve 72 in the same manner as that effected at 60, and viainlet pipe 50 in U.S. Pat. No. 4,528,704, FIG. 2. Alternatively, a flaptype inlet valve 72' to the opposite side, FIG. 32, may be employed forthat purpose. Additionally, the air pallet 10 includes, at twolongitudinally spaced positions on respective sides 10a of the airpallet 10 and integrated to the stack of sheets, U-shaped hand-holds 74coupled thereto via a common base strips 76. Base strips 76 may bethermal bonded or otherwise sealed to the stack of sheets 12, 14, 16 and18, and function as supports for body straps 78, 80, one adjacent toeach of the hand-holds 74. Straps 78, 80 may include, respectively,VELCRO® cooperative mating hook and loop type fastener strips such asthose set forth in U.S. Pat. No. 4,686,719, at 78 and 80.

It should be appreciated that for the air pallet of FIG. 4 of U.S. Pat.No. 4,528,704, the existence of the single array of side-by-side coupledhollow tubes, the air pallet formed thereby shrinks laterally to asignificant degree during gas (air) pressurization of the tubes. Thisresults in a slackening of the thin, flexible bottom sheet 18, and thepossible rendering of the air pallet inoperable, due to the tendency forthe air pallet partially formed thereby to balloon.

The air pallet 10 of the present invention is characterized by meanslimiting lateral shrinkage of the portion of the plenum chamber 68beneath the footprint of the load, as defined by the mass distributionof the patient P, particularly over the lateral width of air bearing A.In the case of the embodiment of FIGS. 26-32, and as shown particularlyin FIG. 32, the thin, flexible sheet 18 as a result of the existence oflongitudinal seal lines 28 sealed to respective faces of sheets 16, 18defining the bottom row of chambers 56, 58 and 62, 64, excess slack iseliminated within the perforated area of the thin, flexible bottom sheet18. The footprint of the air film A then matches or substantiallymatches the footprint of the load P, as a result of the constantpressure maintained within chambers 44-64, inclusive, of the dual rowsof chambers. The full width of sheet 14 acts to form the common wallsfor all tubes of the upper row and all tubes of the lower row, whichcommon walls are rendered taut and rigid under tension, due to fullpressurization of tubes 44-64.

In the embodiment of FIGS. 26-32, it is preferred that the upper section40 of the air pallet 10 include a pressure relief valve as at 82 forlimiting the air pressure in tubes 44 through 64. Under certaincircumstances, the air pallet 10 may include a further thin, flexiblesheet 18', as shown in dotted line, FIG. 32, sealed longitudinally alongthe sides thereof at 84 to the outer edges of the top sheet 12, andlinearly at 86 to certain of the chambers or tubes such as 46, 52. Anair input valve .[.72.]. .Iadd.72" .Iaddend.similar to that for thelower section 42 permits the compressed air pressurization of an upperplenum chamber 88. Further, the fifth thin, flexible sheet 18' in theproposed modification of FIG. 32 includes a central perforated area 24'which mirrors that at 24 of the bottom sheet 18. An air bearing A' maybe created beneath patient P upon pressurization of the upper plenumchamber 88 via compressed air from a source indicated by arrow 89,either alternatively or simultaneously with air bearing A from source70. Such structure may be used with a tent (not shown) to supply amedicament in vapor form about the patient with said tent set over theair pallet 10.

The pressure relief valve 82 automatically maintains the pressurizationof the tubes or chambers within the upper section 40 of the air palletbelow 32 mm of mercury pressure to prevent patient capillary closure.Under such conditions the patient is in therapy, and the function of thepressure relief valve is to regulate the pressure independently of theweight of the patient with the pressure relief valve preferably set toopen at 30 mm of mercury (preset for valve 82). This is particularlydesirable where the air pallet 10 functions as an operating roommattress pad. When patients are in the operating room in a fixed, supineposition, skin breakdown can develop within a very short period of time.The air chambers become near rigid under an air pressure of 32 mm ofmercury, and air pressurization at that level tends to prevent spinalflexure.

The air pallet 10 forming a preferred embodiment of the inventiontherefore constitutes an air chamber-type of flexible air pallet forfrictionless movement of a flexible load supported thereon (patient orinanimate object) relative to an underlying generally planer fixedsupport surface. Such air pallet includes means forming a flexiblegenerally planar backing surface underlying the load. A thin flexiblesheet directly or indirectly underlies the flexible backing surface anddirectly overlies the planar support surface having that portion facingthe generally planar fixed support surface perforated, conforming to thefootprint of the load and defining with the flexible backing surface atleast one plenum chamber. The pin hole perforations open unrestrictedlydirectly to the plenum chamber. The means forming said backing surfacecomprises at least one flexible backing chamber underlying the load. Airdispersion means are operatively associated with the at least one plenumchamber to ensure air flow throughout said at least one plenum chamberwhen the air pallet is under load. The air pallet further comprisesmeans for controlling pillowing of the flexible sheet portion of said atleast one plenum chamber to jack the flexible backing surface and theload sufficiently to permit the air pallet to accommodate surfaceirregularities for both the load support surface and the flexiblebacking surface without balloning. The air pallet includes lateralanti-shrink means for restricting the reduction in air pallet size thatoccurs in a plane parallel to the air bearing during pressurization ofsaid at least one flexible backing chamber. Further, at least one commonmember (sheet 14) is joined at spaced positions, respectively, to saidat least one flexible backing chamber of the upper row of chambers andsaid at least one flexible chamber of the lower row of chambers. Airinlet means 72, .[.82.]. .Iadd.72' .Iaddend.function to pressurize saidchambers to cause said at east one common member to become rigid and tothereby render said flexible, generally planar backing surface at leastsemi-rigid to at least support said load and to produce an air bearingupon jacking of the flexible backing surface and said load above saidfixed support surface by escape of compressed air from said plenumchamber through said perforations. The sheet 14 which has portionscommon to the upper row of tubes and the lower row of tubes form aseries of such linked "common members" or common walls.

By supplying compressed air to multiple stacked chambers there isprovided adequate separation between the flexible load, the flexiblegenerally planar backing surface underlying said load and the generallyplanar fixed support surface irrespective of loss of pressurization in agiven one of said stacked flexible chambers.

FIG. 32a shows a modification of the air pallet 10, at 10' which is ofthe flow through type, using a single source of air under pressure. Airpallet 10' has like elements to that of air pallet 10 bearing likenumerical designations. Additionally holes or ports 38a within sheets 14and 16 permit flow of compressed air from a single source 70 through asingle inlet 72 to flow through the upper and lower rows of tubesdefining multiple stacked backing chambers and thence through plenumchambers 68 via pin hole perforations 26 to form air bearing A.

Referring to FIGS. 33-38, inclusive, a further embodiment of the presentinvention in the form of a flow through soft pad or bladder type airpallet 10" is shown. The air pallet 10" is formed similarly to that ofthe embodiment of FIGS. 26-32 and is created by sewing together, thermalbonding, or heat sealing along narrow linear lines, a plurality of thinflexible sheets, in this case four in number. In air pallet 10", likeelements to the embodiment 10 bear like numeral designations. Furtherthe thin flexible sheet material may be identical to that employed inthe first embodiment. However, in this embodiment, the row of physicallylinked tubes are not under constant air pressure, nor are the chamberscompletely sealed as in the air pallet 10 of FIG. 26. As a result, thesheet material may be other than completely imperforate, and sewing maybe employed to connect the sheets together along seal lines instead ofthermal bonding, in which case slight air leakage may occur at thestitching.

Referring to the drawings, the four sheets are a top sheet indicatedgenerally at 12, a first intermediate sheet indicated generally at 14, apair of opposite hand, second intermediate sheets 16, and a bottom sheetindicated generally at 18. Instead of the sheets being of rectangularform and different sized, the top sheet and bottom sheet 12, 18 areconfigured as a modified octagon having a squared, extended section 13at one, foot end 20; the opposite head end 22 being devoid of suchgenerally rectangular extention. At extension 13 there is provided apair of air input or inlet valves 72 and 72' to the right and left,respectively, at the lateral edges 12a of the top thin flexible sheet12.

The air pallet 10" has particular application as a patient mover;however, it is not generally employed as an air mattress which is aprincipal function of the embodiment of FIG. 26. The first intermediatesheet 14 is, for instance, approximately 6 feet in length, correspondingto the overall length of the air pallet 10". It is of modifiedrectangular plan form, having opposite side edges 14a tapered at 15towards the foot end 20 of the air pallet. The first intermediate sheet14 is provided with four small diameter holes forming air flow ports 17between the upper row tubes partially defined by sheet 14 and the topsheet 12 when sealed together in the manner of FIG. 37 and lower rowtubes defined by sheets 14 and 16. The holes 17 appear within therectangular portion of the sheet 14 closer to the end 22 of the airpallet than end 20.

Two second intermediate sheets 16 are employed in the air pallet 10" andare relatively narrow. They are of modified rectangular planconfiguration, including a rectangular portion 19 which is proximate tohead end 22 of the air pallet 10" and a laterally inward oblique portion21 near the opposite foot end 20 of the air pallet 10". They are each ofgenerally the same length as the air pallet 10" and the balance of thethin flexible sheets making up that assembly. The angulation of portion21 conforms to the tapering of the top and bottom sheets 12, 18 of thelateral sides of those two members at foot end 20. Each of the secondintermediate sheets 16 employed in the structure includes twolongitudinally aligned holes or air flow ports 23 within the rectangularsection 19 of the thin flexible sheet 16.

The thin flexible bottom sheet 18, although configured to that of thetop thin flexible sheet 12, includes a modified perforated area 24bearing thousands of closely spaced pin hole type perforations 26 in themanner of the embodiment .[.of FIG..]. 10 as shown in FIG. 30, withinthe center of sheet 18. The lateral and longitudinal dimensions of thethin flexible sheets for the air pallets 10 and 10' may be generallyidentical, as well as the perforated area 24 of each bottom sheet 18 forthe respective embodiments. The size of the perforated area 24 isdetermined by the mass of the patient or other load transported by theair pallet and the mass distribution of that load. The mass of a humanbody lies principally in the trunk, and this is the area of perforationdisposition such that the footprint of the load conforms to theperforated area 24 of sheet 18, and thus the footprint of the airbearing A created beneath the bottom thin flexible sheet 18.

These general relationships exist for all of the embodiments of theinvention described herein, and as shown in the drawings accompanyingthis description including embodiments 10, 10' and 10". The stackedsheets for air pallet 10" at 12, 14, 16 and 18 are illustratedschematically in FIG. 37 vertically separated so that the generation ofthe tube array may be appreciated in the completion of the air palletstructure by seam sewing, thermal bonding, or the like, at predeterminedpositions, and along lines extending over given lengths of the stackedlayers of sheets. By reference to the various FIGS. 33-37, inclusive,with the thin flexible bottom sheet in place, a pair of opposite hand,second intermediate sheets 16 are positioned on sheet 18 and are bondedthereto along opposite lateral side edges via seal lines 28 over thefull length of the air pallet, as evidenced in FIG. 35. Next, a firstintermediate thin flexible sheet 14 is positioned so that its oppositelateral edges 14a overlap portions of the opposite hand sheets 16, andwith sheet 14 centered laterally of the assembly of sheets 14, 16, 18.As may be appreciated, as per FIG. 34, laterally spaced, longitudinalseal lines are effected between sheet 14 and respective opposite handsheets 16 as at 30 adjacent the lateral sides 14a the first intermediatethin flexible sheet 14. Those seal lines may be effected simultaneouswith seal lines bonding the thin flexible sheet 14 to the top thinflexible sheet 12. In order to effect that action, it is preferable toinsert a backing anvil positioned beneath the thin flexible oppositehand sheets 16 at the location of the two longitudinally extendingparallel seal lines 30. If stitching is to be employed in the creationof the seal lines demarcating the various tubes or chambers, such anvilor backing member is not necessary. Lastly, the thin flexible top sheet12 is placed on top of thin flexible sheet 14 completing the array. Allfour sheets 12, 14, 16 and 18 are sewn or thermo bonded together alongtop and bottom edges thereof. In this embodiment, five laterally spaced,longitudinally extending seal lines 32 are required to complete theassembly, including a seal line 32 at the lateral center, FIG. 33, toeach side thereof and aligned with or supplementing seal lines 30extending through the first intermediate sheet 14 and the opposite handsheets 16, as per FIG. 37. Outer edge seal lines 32 are effected solelybetween the top thin flexible sheet 12 and bottom sheet 18 along thelateral edges of sheets 12 and 18. Since this is a compressed air flowthrough type "soft pad" air pallet, the seal lines do not have tocompletely seal off the various tubes formed thereby. Air flow which isinitiated from inlet valve 72 or 72', via source 70 at end 20 of the airpallet 10" passes through four upper tubes or chambers 45, 47, 49 and51, FIG. 37, and then via the small diameter ports 17 into central tubeor chamber 55 of the lower row of tubes, and simultaneously by holes orports 23 within the opposite hand intermediate thin flexible sheets 16into the chamber or tubes 53 and 57 of the lower row of tubes. For flowto occur and for air pressurization of the chambers to occursimultaneously, smoothly in longitudinal progression and at equalpressure, the laterally central seal line 32 initiates at some distancefrom end 20 of the air pallet 10" and extends completely to the oppositeend 22 of the air pallet. Seal lines 32 to opposite sides of the centerseal line are initiated closer to end 20 and terminate short of end 22by a distance of approximately 2 inches in this embodiment 10" which isapproximately 6 feet in length. As a result, there is no jolt to thepatient lying thereon, or a series of jolts by unequal airpressurization through parallel tubes with head jolt upon lift duringjacking of the patient due to air flow through the row of tubes formingflexible backing chambers defined by three of the four sheets 12, 14, 16upon air pressurization. In FIG. 34 the sewn seal line 32, common withthe top sheet 12 is indicated on the first intermediate sheet 14.Additionally, seal lines 30 extend from a point near the pallet airinlet foot end 20, but not at that end, and continue towards theopposite end 22, but terminate short of that end by approximately threeinches in the illustrated embodiment. This permits air equalizationwithin at least all upper tubes forming flexible backing chambers 45,47, 49 and 51 and eliminates patient trauma induced jolts. From FIG. 35it may be seen that the laterally spaced seal lines 28, sealing lateraledges of the opposite hand sheets 16 to the bottom sheet 18 extend overthe full length of the air pallet 10' from foot the air inlet foot end20 to the opposite head end 22. As shown in FIG. 35, the seal lines 30sealing a lateral edge of intermediate sheet 14 to the near lateralcenter of the opposite hand intermediate sheets 16 are initiated at somedistance from the air inlet, foot end 20, and terminate short of theopposite head end 22.

Air pressurization is achieved through an inlet valve 72, schematicallyillustrated as a relatively small diameter tube in FIGS. 37 and 38, withthe compressed air emanating from a supply or source indicatedschematically by arrow 70. Air pressurization of the upper row offlexible backing chambers 45, 47, 49 and 51 is higher than that of thelower row of laterally offset, integrated tubes forming multiple plenumchambers 53, 55 and 57 defining air bearing A since the air enters thelower tubes from the upper row tubes through the multiple small diameterholes or air flow ports 23, 17. Preferably there are two or morelongitudinally spaced holes feeding air from a respective upper row tubeto a lower row tube.

Unlike the embodiment of FIG. 26, the patient mover type air pallet 10"of FIGS. 33-38 has no means for providing rigidity due to the nature ofthe construction and configuration of the upper tubes defined by sheets12, 14. The air inlet valves 72, 72' may take appropriate form, such asthat shown in U.S. Pat. Nos. 4,272,856 and 4,528,704. These valvesautomatically self seal when not in use so that the valves 71, 72' maybe alternatively employed. In patient mover use, the end 20 becomes thefoot end of the patient mover air pallet 10' and the opposite end 22 thehead end. Air pressurization causes the collapsed thin flexible sheetformed soft pad air pallet 10" to initially fill the upper row flexiblebacking chamber tubes 45, 47, 49 and 51 and then the lower row plenumchamber tubes 53, 55 and 57 in sequence prior to the creation of the airbearing A by escape of the air flow through the perforations 26. In thiscase, the feet of the patient P are initially jacked prior to jacking ofthe patient's head. Trauma is not produced since the gas pressurizationis uniform in development, and equal for respective tubes of the upperrow tube array, and with the air pressure within the tubes of the lowerrow or array being slightly less due to the pressure drop caused by theair passage holes 17, 23. FIG. 38 shows the severe actions of hotdogging of air pallet 10" upon air pressurization, principally due tothe size and lack of anti-shrink prevention means within central plenumchamber 55.

The air pallet 10", with the exception of spacing the head endlongitudinal seal lines 32, 30 from the transverse seal line 34 at theedge of the air pallet 10 (commonly sealing off all sheets 12, 14, 16,18 along narrower linear surface areas) is considered to be prior art tothe subject matter of this invention. Further, certain of the means forcontrolling performance of air pallet 10" have basis in U.S. Pat. Nos.3,948,844 and 4,417,639.

The shrink prevention means for patient mover 10 and lacking in patientmover 10" or like air pallets may take various forms and the geometryfor creating structure providing that function may consist solely inthin flexible film material or the incorporation of semi-rigid orgenerally rigid elements of solid or hollow frame construction.

FIG. 39 is a vertical sectional transverse sectional view of a furtherpatient mover type air pallet 10'" as a modification of the air pallet10, FIG. 26-32, which, and in all other respects includes the content ofthe drawing figures of that embodiment with like elements using likenumerical designations. Air pallet 10'" utilizes the same four thinflexible sheets. a top sheet 12, a bottom sheet 18, two intermediatesheets 14, 16 to make up the thin flexible film formed structure forsupporting a patient such as at P. Air pallet 10'" incorporates anadditional intermediate thin flexible sheet 25 positioned between sheets16 and 18 and edge sealed thereabouts on three sides, thus forming abacking member cavity 27 therebetween. A generally rigid board or sheetsuch as sheet 29, is provided within cavity 27 constituting additionallateral anti-shrink means for segmented plenum chamber 31. Additionally,in FIG. .[.40.]. .Iadd.39, .Iaddend.this embodiment has the firstintermediate sheet 14 imperforate, and accordion pleated with the edgesof the pleats as at 33, thermal bonded or otherwise sealedlongitudinally, alternatively to respective opposing surfaces of the topsheet 12 and the second intermediate sheet 16 to form closed sealedflexible backing chambers or tubes similar to that of FIG. 24. Theseconsist of an upper row of chambers or sealed hollow tubes 35 and alower row of such tubes 37 with common walls 41 subjected topressurization on opposite sides by a chamber 35 and 37, respectively.Since the corrugated walls are common to two tubes, one on each side ofan oblique wall, such common walls are rendered taut or rigid acting asI beams and this structure resists the tendency for the air pallet tohot dog. i.e., the opposite lateral edges to curl in response to gaspressurization of these chambers. Sheet 29 may be dispensed with sincethe flexible backing chambers render the air pallet generally rigid uponair pressurization. Additionally, the bottom thin flexible sheet 18 overthe extent of the lateral perforated area beating perforations 26, formsa series of adjacent plenum chambers or chamber sections 31 with thesheet 18 bonded to the bottom of the thin flexible sheet 25 at laterallyspaced seal lines 39 which extend longitudinally and which additionallyassist in maintaining the air bearing at A. Air under pressure issupplied through air inlet valve 72' to the left, and via a commontransverse manifold (not shown) open to the balance of the segmentalplenum chamber 31.

Alternatively a rigid rectangular open frame .[.41..]..Iadd.29'.Iaddend., FIG. 40, may be inserted within backing membercavity 27, FIG. 39, whose longitudinally extending, laterally spacedbeams .[.41a.]. .Iadd.29'a .Iaddend.prevent lateral shrinking of theplenum chamber 31 such that the footprint of the air bearing A remainsadequately sized for the footprint of the mass distribution of the load(patient P) positioned on the upper surface of the top thin flexiblesheet 12. In a variation, the patient mover air pallet 10'" could bepositioned within the frame .[.41.]. .Iadd.29'.Iaddend. opening andstrung on the frame by tensioned cords with the frame providing anexterior anti-shrink function.

Turning next to FIG. 41, a further embodiment of the patient mover typeair pallet 10"" is illustrated, again being a vertical sectional viewcorresponding to the air pallet 10 embodiment shown in FIG. 32 withmodifications as shown in the drawings. Otherwise the air pallet 10""corresponds to air pallet 10, as described and shown in detail. Onerespect in which the structure 10"" is modified resides in theutilization of vertical and oblique ties 43 formed of perforatedflexible sheet material, being thermal bonded, sewn, heat sealed or thelike at opposite ends to the thin flexible perforated bottom sheet 18and to the second intermediate sheet 16 respectively. These ties 43 act,when taut, as additional physical restraints to prevent the structurefrom hot dogging. in response to air pressurization of the upper andlower rows of tubes 44 through 64, inclusive and the plenum chamber.While the dual tube array in FIG. 41 corresponding to FIG. 32, by havingcommon walls of side by side laterally offset upper and lower rowflexible backing chamber tubes, equally pressurized, normally adequatelyprevents excessive shrinkage of the portion of the plenum chamber 68forming the air bearing A such that the footprint of the air bearing Abetween the air pallet 10"" and the rigid planar support surface 11beyond that capable of supporting the load P over its footprint, theties 43 further assist in that purpose. Such ties may in themselvessolely provide that function in a soft pad or hard pad air pallet. Withthe tubes 44-64 under constant pressure by application of compressed airto the tubes as per arrow 89 similar to the embodiment of FIG. .[.26.]..Iadd.32.Iaddend., the application of a low cfm flow of air from asource indicated as arrow 70 through the air inlet valve 72 to plenumchamber 68 creates the air bearing A over a perforated area whosefootprint may be readily maintained between 75% and 100% of thefootprint cross sectional area of the load provided by the patient Psupported by the pallet 10"".

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formand details may be made therein without departing from the spirit andscope of the invention.

What is claimed is:
 1. A patient mover air pallet for frictionlessmovement of a patient over an underlying, relatively fixed supportsurface, said patient mover air pallet comprising:top, intermediate andbottom thin flexible sheets, means for sealing given sheets togetherlinearly to define a plenum chamber between said intermediate and bottomsheets, .[.at least one backing member cavity between said top sheet andsaid intermediate sheet,.]. said bottom thin flexible sheet including aportion defined by the footprint of the load having a plurality ofclosely spaced small diameter pin hole type perforations openingdirectly into the plenum chamber and directly onto said support surface,air inlet means communicating with the plenum chamber at one end thereoffor permitting low pressure air flow pressurization of the plenumchamber for initially jacking the load and for subsequent dischargethrough the perforations to create a thin air film between the bottomthin flexible sheet and the support surface, means including said topthin flexible sheet defining a semi-rigid backing member so as to definewith the plenum chamber air dispersion means for insuring air flowthroughout the plenum chamber when the air pallet is under load at thetime of air pressurization of the plenum chamber.Iadd., .Iaddend.andconstituting with said bottom thin flexible sheet.[.,.]. means forcontrolling pillowing of the thin flexible sheet material to permitjacking of the semi-rigid backing member and the load while preventingballooning of the thin flexible sheet material, wherein said semi-rigidbacking member permits deflection of the patient mover somewhat toconform the patient mover to depressions within the support surface topermit transport of the patient via the patient mover air pallet oversaid support surface.Iadd.,.Iaddend. wherein said top thin flexiblesheet is sealed to said intermediate thin flexible sheet alonglongitudinal parallel lines at laterally spaced positions across thesurface of the intermediate thin flexible sheet and at both ends thereofto form a series of longitudinally extending tubes, and wherein meansare provided for supplying air under pressure to the individual tubesformed thereby in addition to air pressurization of the plenum chambersuch that the tubes cradle the patient while facilitating transport ofthe patient over the support surface on the frictionless air film, theimprovement comprising means for substantially restricting lateralshrinkage of the portion of the plenum chamber in the area of saidperforations parallel to the plane of the developed air film formaintaining the footprint of the air film generally equal to that of thefootprint of the load to insure stable support of the patient on thepatient mover air pallet, and for preventing loss of said air film andgrounding of the air pallet to the underlying support surface.
 2. Thepatient mover air pallet as claimed in claim 1.Iadd., .Iaddend.whereinsaid means for substantially restricting lateral shrinkage of saidplenum chamber over the width of said perforated portion of said thinflexible bottom sheet comprises two integral, linked vertical rows ofsaid tubes extending transversely with the tubes of one row beinglaterally offset with respect to the other over the full lateral widthof the perforated portion of the thin flexible bottom sheet such thatthe centers of tubes in one row are aligned with abutting peripheries oftubes of the adjacent row and adjacent tubes of said two rows have acommon wall under pressurization to opposite sides rendered thereby.[.taunt.]. .Iadd.taut .Iaddend.and rigid, and wherein said taut commonwalls render said two rows of tubes rigid under said load to stablysupport said load thereon.
 3. The patient mover air pallet as claimed inclaim 2.Iadd., .Iaddend.wherein said linked rows of tubes are sealedfrom said plenum chamber, and means are provided for separatelysupplying compressed air to said linked rows of tubes from that suppliedto said at least one plenum chamber.
 4. The patient mover air pallet asclaimed in claim 3, further comprising a pressure relief valveoperatively coupled to said linked rows of tubes and set to prevent thepressure therein from reaching a level inducing capillary closure of thepatient supported by said patient mover air pallet.
 5. The patient moverair pallet as claimed in claim 4, wherein said pressure relief valve isa variably adjustable valve such that said linked rows of tubes can belightly air pressurized to form a highly supple comfortable air mattressfor supporting a patient thereon over long periods of time withouttrauma, while providing therapy to said patient.
 6. The patient moverair pallet as claimed in claim 2, wherein at least one of said tubesconstituting said semi-rigid backing member carries said air inlet meansat one end thereof opening directly thereto, and wherein at an oppositeend thereof, an air flow port opens to an integral linked tube ofanother row of tubes to permit flow of low pressure air flow from onetube of one of said rows to said tube of another row via said air flowport and wherein the cross-sectional area of said air flow port issubstantially less than the cross-sectional area of said air inlet meanssuch that said one tube of said one linked row is at a higher pressurethan said other tube of said another linked row of tubes.
 7. The patientmover air pallet as claimed in claim 2, wherein openings are providedwithin said tubes of one row which open directly into tubes of theadjacent row, and wherein said tubes of said one or said adjacent rowhave further openings which open directly into the plenum chamber, andwherein at least one of said tubes of one of said rows carries air inletmeans at one end thereof opening directly thereto, such that saidpatient mover air pallet constitutes a flow through soft pad with saidflow of air being through said tubes of integral linked rows, andthrough said plenum chamber to effect said means for substantiallyrestricting lateral shrinkage of the plenum chamber, while providingsimultaneously said air film.
 8. The patient mover air pallet as claimedin claim 2, wherein .Iadd.said .Iaddend.air pallet includes asecond.[.,.]. intermediate thin flexible sheet, said secondintermediate.[.,.]. thin flexible sheet is interposed between said firstintermediate thin flexible sheet and said top sheet, and wherein saidmeans for sealing given sheets together linearly comprise seal linesextending longitudinally over a given length of said thin flexiblesheets at laterally spaced positions, such that said integral linkedrows of .[.end-to-end.]. tubes are formed solely by said top and bottomthin flexible sheets and said first and second intermediate thinflexible sheets, and seal lines extending at least between twoimmediately adjacent flexible sheets.
 9. The patient mover air pallet asclaimed in claim 8, wherein said intermediate thin flexible sheetsinclude holes therein forming air flow ports between respective tubesdefined by said at least two immediately adjacent sheets and betweenlaterally spaced seal lines for permitting air pressurization of aplurality of tubes formed thereby from a common source of air underpressure.
 10. The patient mover air pallet as claimed in claim 8,wherein said bottom thin flexible sheet bearing said perforationsincludes means for coupling said bottom thin flexible sheet to saidimmediately adjacent intermediate thin flexible sheet at laterallyspaced positions substantially across the extent of said area ofperforations, so as to provide individual segments to said plenumchamber to prevent excessive slack in said bottom thin flexible sheetand bottoming out of the patient on the underlying relatively fixedsupport surface during air pallet operation and hot dogging of said airpallet.
 11. The .[.patent.]. .Iadd.patient .Iaddend.mover air pallet asclaimed in claim 8, further comprising a third.[.,.]. intermediate thinflexible sheet edge sealed to intermediate thin flexible sheets toopposite sides thereof, and defining a backing member cavity, andwhereina generally rigid backing member is carried within said cavity andcomprises part of said means for substantially restricting lateralshrinkage of said plenum chamber over at least the width of saidperforated portion of said bottom thin flexible sheet.
 12. The patientmover air pallet as claimed in claim 8, wherein said means forsubstantially restricting lateral shrinking of said plenum chamber overat least the width of said perforated portion of said thin flexiblebottom sheet comprises ties within said plenum chamber, having oppositeends fixed respectively to said bottom thin flexible sheet and saidintermediate thin flexible sheet proximate thereto forming said integrallinked rows of tubes extending transversely across the width of said airpallet.
 13. The patient mover air pallet as claimed in claim 12, whereinsaid ties extend perpendicularly through said plenum chamber at rightangles to the plane of said air film and that of the patient supportedthereby.
 14. The patient mover air pallet as claimed in claim 12,wherein said ties extend obliquely from said bottom thin flexible sheetinwardly towards the center of said plenum chamber to engage saidintegral linked rows of tubes to restrict movement of said bottom thinflexible sheet away from the integral linked rows of tubes and towardsthe respective lateral sides of said patient mover air pallet.
 15. Aflexible air pallet for frictionless movement of a flexible loadsupported thereon relative to an underlying generally planar fixedsupport surface, said air pallet including:a first thin flexible sheetforming a flexible, generally planar backing surface underlying theload, a second thin, flexible sheet underlying the flexible backingsurface and directly overlying the planar support surface, said secondthin, flexible sheet having a portion facing the generally planar fixedsupport surface perforated over a surface area generally conforming tothe footprint of the load and defining with the flexible backingsurface, at least one plenum chamber, said perforations openingunrestrictedly directly to the plenum chamber, air dispersion meansoperatively associated with said at least one plenum chamber to insureair flow throughout said at least one plenum chamber when the air palletis under load, means for controlling pillowing of the thin, flexiblesheet portion of said at least one plenum chamber to jack the flexiblebacking surface and the load sufficiently to permit the air pallet toaccommodate surface irregularities for both the load support surface andthe flexible backing surface without ballooning, and air inlet means forsupplying compressed air to said at least one plenum chamber, theimprovements wherein said air pallet includes within said at least oneplenum chamber, at least one flexible common member joined at spacedpositions respectively to said first and second flexible sheets withinthe perforaed area underlying the footprint of the load and being oflimited length, whereby said air inlet means in supplying air underpressure to said at least one plenum chamber causes said at least onecommon member to become taut and rigid and to thereby render saidflexible, generally planar backing surface at least semi rigid to atleast support said load and to produce an air film upon jacking of theflexible backing surface and the load above said fixed support surfaceby escape of compressed air from said at least one plenum chamberthrough said perforations, and said at least one flexible common memberdefining lateral anti-shrink means for restricting the reduction in airpallet size in a plane parallel to the air film during airpressurization of said at least one plenum chamber.
 16. The air palletas claimed in claim 15, wherein said at least one flexible member is athird thin, flexible sheet joined at lateral spaced positionsalternatively to said first and second thin flexible sheets.
 17. The airpallet as claimed in claim 16, whereinsaid third thin flexible sheetcomprises a series of unitary portions common to an upper row of tubesand a lower row of tubes, said upper row of tubes defining pluralflexible backing chambers, and said lower row of tubes defining aplurality of linked plenum chambers, and wherein, said upper and lowerrows of tubes extend completely across the area of said perforations andprovide adequate separation between the flexible load, the flexiblegenerally planar backing surface underlying the load and the generallyplanar fixed support surface, irrespective of loss of pressurization ina given one of said tubes of either of said rows of tubes.
 18. Aflexible air chamber-type air pallet for frictionless movement of a load.[.support.]. .Iadd.supported .Iaddend.thereon relative to an underlyinggenerally planar fixed support surface, said air pallet being formed ofthin, flexible sheet material consisting of a first thin, flexible sheetat least partially defining a flexible, generally planar backing surfacefor supporting said load thereon, anda second thin, flexible sheetdirectly underlying and sealed to said backing surface and directlyoverlying said fixed load support surface and being sealed thereto alonglongitudinal lines at laterally spaced positions to form a series oflaterally connected plenum chambers, said second thin, flexible sheethaving a plurality of perforations therein facing said fixed supportsurface within said linked plenum chambers, said perforations openingdirectly into and out of said plenum chambers, air dispersion means forsaid plenum chambers to insure air flow through said chambers when saidair pallet is under load, air inlet means to said chambers for directingcompressed air into said plenum chambers for jacking said load and fordischarge of said air from the plenum chambers through said perforationsto create an air film between said thin, flexible bottom sheet and saidfixed support surface, pillowing means to cause, upon air pressurizationof said chambers.Iadd., .Iaddend.said thin, flexible sheet portions ofsaid chambers to jack the backing surface and said load sufficiently topermit the pallet to accommodate surface irregularities and to move saidload on said air film, means for rendering said plenum chamberssufficiently rigid under said load to support said load when saidchambers are pressurized, and means for limiting the amount of lateralshrink across the air pallet upon air pressurization of said plenumchambers so that said air pallet plenum chambers can lift said load. 19.The flexible air chamber-type air pallet as claimed in claim 18, furthercomprising:means for rendering said plenum chambers in the area of saidperforations sufficiently rigid to prevent load instability and toprevent hot dogging of said linked plenum chambers underlying said load.20. The air pallet as claimed in claim 18, wherein said first thin,flexible sheet is joined to said second thin, flexible bottom sheet bylongitudinally extending parallel seal lines to form a side-to-sidearray of parallel tubes, with the lateral width between the seal linesfor one of said thin, flexible sheets being significantly different fromthat of the other thin, flexible sheet, thereby providing inherently thetendency to arch the thin, flexible sheet whose lateral width betweenadjacent parallel seal lines is narrower than that of the other thin,flexible sheet, upon air pressurization of the linked plenum chambers.21. Said flexible air chamber-type air pallet as claimed in claim 20,wherein said air pallet comprises hollow tubes extending generally atright angles to said side-to-side array of tubes defined by said firstand second thin, flexible sheets at both sides thereof and constitutingsaid means for rendering said air pallet plenum chambers generally rigidto prevent load instability and for preventing grounding and insuringthat the load is jacked sufficiently from the underlying fixed supportsurface to permit the pallet to accommodate surface irregularities andto move said load on said air film.
 22. The flexible air chamber-typeair pallet as claimed in claim 18, wherein said thin, flexible bottomsheet tends to flatten in the vicinity of the underlying relativelyfixed support surface under load, when said chambers are airpressurized, andwherein the perforations within said plenum chambersexist solely within the flattened area of said thin, flexible bottomsheet for each of said plenum chambers, thereby maintaining thefootprint of the developed air film sized to that of said load.
 23. Aflexible film air chamber-type air pallet for frictionless movement of aload supported thereon relative to an underlying generally planar fixedsupport surface, said air pallet comprising:a flexible, generally planarbacking surface for supporting said load thereon, a thin, flexible sheetdirectly underlying said flexible backing surface and directly overlyingsaid load support surface, a portion of said thin, flexible sheet facingsaid general planar fixed support surface being perforated and beingsealed to and defining with said backing surface at least one plenumchamber, said perforations extending over an area generallycorresponding to the footprint of the load with said perforationsopening directly into said at least one plenum chamber, air dispersionmeans for said plenum chamber to insure air flow through said chamberwhen said chamber is under load and being pressurized, air inlet meansopening to said at least one plenum chamber for permitting air underpressure to enter into the plenum chamber for jacking said load, fordischarge of the air from said plenum chamber through said perforationsto create an air film between the flexible, thin sheet and said fixedsupport surface over the area of the perforations, pillowing means forjacking the backing surface and said load sufficiently to permit thepallet to accommodate surface irregularities and move said load on afilm of air without said thin, flexible bottom sheet ballooning, meansfor preventing said at least one plenum chamber from .[.hot dogging.]..Iadd.hotdogging, .Iaddend.for preventing load instability.Iadd.,.Iaddend.and for maintaining said at least one plenum chamber planar ina direction parallel to the developed air film for retention of the loadon said backing surface during movement of said load via said air palleton said developed air film, and means for limiting shrink of the airpallet laterally parallel to the plane of the developed air film overthe surface area of the perforations to insure that the footprint of theair film generally matches that of the load.
 24. The flexible airchamber-type air pallet as claimed in claim 23, further comprising meansfor rendering said flexible generally planar backing surface rigid undersaid load to support said load upon jacking when said at least oneplenum chamber is air pressurized.
 25. In a flexible air chamber-typeair pallet for frictionless movement of a load supported thereonrelative to an underlying generally planar fixed support surface, saidair pallet being formed of thin, flexible sheet material comprising afirst thin, flexible sheet at least partially defining a flexible,generally planar backing surface for supporting said lead thereon, andasecond thin, flexible sheet underlying said backing surface and directlyoverlying said fixed load support surface and being connected theretoalong longitudinal lines at laterally spaced positions to form a seriesof laterally connected, linked plenum chambers, said second thin,flexible sheet having a plurality of perforations therein facing saidfixed support surface within said linked plenum chambers, saidperforations opening directly into and out of said plenum chambers, airdispersion means for said plenum chambers to insure air flow throughsaid chambers when said air pallet is under load, air inlet means tosaid chambers for directing compressed air into said plenum chambers forjacking said load and for discharge of said air from the plenum chambersthrough said perforations to create an air film between said thin,flexible bottom sheet and said fixed support surface, pillowing means tocause, upon air pressurization of said chambers said thin, flexiblesheet portions of said chambers to jack the backing surface and saidload sufficiently to permit the pallet to accommodate surfaceirregularities and to move said load on said air film, the improvementcomprising: means for controlling the amount of lateral shrink acrossthe pallet upon air pressurization of said plenum chambers so that saidair pallet plenum chambers can lift said load, and means for renderingsaid first thin flexible sheet over the area of said perforationssufficiently rigid to support said load when the chambers arepressurized and means to prevent load instability and .[.hot dogging.]..Iadd.hotdogging .Iaddend.of said air pallet under load.
 26. A flexiblefilm air chamber-type air pallet for frictionless movement of a loadsupported thereon relative to an underlying generally planar fixedsupport surface, said air pallet comprising:a flexible, generally planarbacking surface for supporting said load thereon, a thin, flexible sheetunderlying said flexible backing surface and directly overlying saidload support surface, a portion of said thin, flexible sheet facing saidgenerally planar fixed support surface being perforated and being sealedto and defining with said backing surface at least one plenum chamber,said perforations extending over a surface area of said thin, flexiblesheet corresponding generally to the footprint of the load with saidperforations opening directly into said at least one plenum chambers,air dispersion means for said plenum chamber to insure air flow throughsaid chamber when said chamber is under load and being pressurized, airinlet means opening to said at least one plenum chamber for permittingair under pressure to enter the at least one plenum chamber for jackingsaid load, and for discharge of the air from said plenum chamber throughsaid perforations to create an air film between the flexible, thin sheetand said fixed support surface over the area of the perforations,pillowing means for jacking the backing surface and said loadsufficiently to permit the pallet to accommodate surface irregularitiesand move said load on a film of air without said thin, flexible bottomsheet ballooning, and means for preventing said at least one plenumchamber from .[.hot dogging.]. .Iadd.hotdogging.Iaddend., for preventingload instability, for maintatining said flexible backing surface planarin a direction generally parallel to the developed air film forretention of the load on said backing surface during movement of saidload via said air pallet on said developed air film and for limitingshrink of the air pallet laterally, generally parallel to the plane ofthe developed air film to insure that the footprint of the air filmgenerally matches that of the load, and means for rendering saidflexible generally planar backing surface sufficiently rigid under saidload to support said load upon jacking when said at least one plenumchamber is air pressurized. .Iadd.
 27. The patient mover air pallet asclaimed in claim 8, wherein said integral linked rows of tubes aresealed from said plenum chamber, and means are provided for separatelysupplying compressed air to said linked rows of tubes from that suppliedto said at least one plenum chamber. .Iaddend..Iadd.28. The patientmover air pallet as claimed in claim 27, further comprising a pressurerelief valve operatively coupled to said linked rows of tubes and set toprevent the pressure therein from reaching a level inducing capillaryclosure of the patient supported by said patient mover air pallet..Iaddend..Iadd.29. The patient mover air pallet as claimed in claim 28,wherein said pressure relief valve is a variably adjustable valve suchthat said integral linked rows of tubes can be lightly air pressurizedto form a highly supple comfortable air mattress for supporting apatient thereon over long periods of time without trauma, whileproviding therapy to said patient. .Iaddend..Iadd.30. The patient moverair pallet as claimed in claim 12, wherein said ties extendperpendicularly through said plenum chamber at right angles to the planeof said air film and that of the patient supported thereby and obliquelyfrom said bottom thin flexible sheet inwardly towards the center of saidplenum chamber to engage said integral linked rows of tubes to restrictmovement of said bottom thin flexible sheet away from the integrallinked rows of tubes and towards the respective lateral sides of saidpatient mover air pallet. .Iaddend..Iadd.31. The patient mover airpallet as claimed in claim 2, further comprising another thin flexiblesheet sealed to the top thin flexible sheet along the edges thereof andsealed along lines extending transversely across said air pallet to thetop thin flexible sheet, including a perforated area having a pluralityof closely spaced small diameter pinhole-type perforations openingupward towards the load for creating a second air bearing, defining anupper plenum chamber directly beneath the patient supported by saidpatient mover air pallet. .Iaddend..Iadd.32. The patient mover airpallet as claimed in claim 31, wherein said upper plenum chamber, whenpressurized from a source of compressed air, provides sufficientlubrication for patient positioning on the air pallet..Iaddend..Iadd.33. The patient mover air pallet as claimed in claim 31,wherein said upper plenum chamber, upon pressurization from a separatesource of compressed air, can be utilized to supply a medicament invapor form upwards about the patient supported by the air pallet..Iaddend..Iadd.34. The patient mover air pallet as claimed in claim 8,further comprising another thin flexible sheet sealed to the top thinflexible sheet along the edges thereof and sealed along lines extendingtransversely across said air pallet to the top thin flexible sheet,including a perforated area having a plurality of closely spaced smalldiameter pinhole-type perforations opening upward towards the load forcreating a second air bearing, defining an upper plenum chamber directlybeneath the patient supported by said patient mover air pallet..Iaddend..Iadd.35. The patient mover air pallet as claimed in claim 34,wherein said upper plenum chamber, when pressurized from a source ofcompressed air, provides sufficient lubrication for patient positioningon the air pallet. .Iaddend..Iadd.36. The patient mover air pallet asclaimed in claim 34, wherein said upper plenum chamber, uponpressurization from a separate source of compressed air, can be utilizedto supply a medicament in vapor form upwards about the patient supportedby the air pallet. .Iaddend..Iadd.37. The patient mover air pallet asclaimed in claim 8, wherein at least one of said tubes constituting saidsemi-rigid backing member carries said air inlet means at one endthereof opening directly thereto, and wherein at an opposite endthereof, an air flow port opens to an integral linked tube of anotherrow of tubes to permit flow of low pressure air flow from one tube ofone of said rows to said tube of another row via said air flow port andwherein the cross-sectional area of said air flow port is substantiallyless than the cross-sectional area of said air inlet means such thatsaid one tube of said one linked row is at a higher pressure than saidother tube of said another linked row of tubes. .Iaddend..Iadd.38. Thepatient mover air pallet as claimed in claim 8, wherein openings areprovided within said tubes of one row which open directly into tubes ofthe adjacent row, and wherein said tubes of said one or said adjacentrow have further openings which open directly into the plenum chamber,and wherein at least one of said tubes of one of said rows carries airinlet means at one end thereof opening directly thereto, such that saidpatient mover air pallet constitutes a flow through soft pad with saidflow of air being through said tubes of integral linked rows, andthrough said plenum chamber to effect said means for substantiallyrestricting lateral shrinkage of the plenum chamber, while providingsimultaneously said air film. .Iaddend..Iadd.39. The flexible air palletas claimed in claim 17 wherein said flexible backing chambers are sealedfrom said plenum chambers, and means are provided for separatelysupplying compressed air to said backing chambers from that supplied tosaid plenum chambers. .Iaddend..Iadd.40. The flexible air pallet asclaimed in claim 39, further comprising a pressure relief valveoperatively coupled to said flexible backing chambers and set to preventthe pressure therein from reaching a level inducing capillary closure ofthe patient supported by said patient mover air pallet..Iaddend..Iadd.41. The flexible air pallet as claimed in claim 40,wherein said pressure relief valve is a variably adjustable valve suchthat said flexible backing chambers can be lightly air pressurized toform a highly supple comfortable air mattress for supporting a patientthereon over long periods of time without trauma, while providingtherapy to said patient. .Iaddend..Iadd.42. The flexible air pallet asclaimed in claim 17, wherein at least one of said tubes constitutingsaid semi-rigid backing surface carries said air inlet means at one endthereof opening directly thereto, and wherein at an opposite endthereof, an air flow port opens to an integral linked tube of anotherrow of tubes to permit flow of low pressure air flow from one tube ofone of said rows to said tube of another row via said air flow port andwherein the cross-sectional area of said air flow port is substantiallyless than the cross-sectional area of said air inlet means such thatsaid one tube of said one linked row is at a higher pressure than saidother tube of said another linked row of tubes. .Iaddend..Iadd.43. Theflexible air pallet as claimed in claim 17, wherein openings areprovided within said tubes of one row which open directly into tubes ofan adjacent row, and wherein said tubes of said one or said adjacent rowhave further openings which open directly into said at least one plenumchamber, and wherein at least one of said tubes of one of said rowscarries air inlet means at one end thereof opening directly thereto,such that said air pallet constitutes a flow through soft pad with saidflow of air being through said tubes of linked rows, and through saidplenum chamber to effect said means for substantially restrictinglateral shrinkage of the plenum chamber, while providing simultaneouslysaid air film. .Iaddend..Iadd.44. The flexible air pallet as claimed inclaim 17, wherein said rows of tubes generally extend longitudinallyalong the air pallet. .Iaddend..Iadd.45. The flexible air pallet asclaimed in claim 17, wherein said rows of tubes generally extendlaterally across the air pallet. .Iaddend..Iadd.46. The flexible airpallet as claimed in claim 17, further comprising means for eliminatingtrauma to the head and neck of a patient supported on the air palletinduced by jolts received from unequal air pressurization of the row oftubes forming the flexible backing chambers. .Iaddend..Iadd.47. Theflexible air pallet as claimed in claim 46, wherein said means foreliminating trauma to the head and neck of a patient comprises air flowpaths between the ends of the tubes and the opposing edge of the airpallet, said air flow path having a pre-determined minimum dimension..Iaddend..Iadd.48. The flexible air chamber-type air pallet as claimedin claim 24, wherein said means for rendering said backing surface rigidcomprises at least one row of tubes with each tube of said row of tubeshaving a common wall with said at least one plenum chamber, said commonwalls of said tubes, under pressurization, rendering said at least onerow of tubes rigid under said load to stably support said load thereon..Iaddend..Iadd.49. The flexible air chamber-type air pallet as claimedin claim 23, wherein said means for limiting shrink of the air palletcomprises two integral, linked vertical rows of tubes with a first rowbeing laterally offset with respect to a second row such that thecenters of the tubes in the first row are aligned with abuttingperipheries of tubes of the second row and adjacent tubes of said tworows having a common wall under pressurization to opposite sides beingrendered taut and rigid, wherein said rows of tubes comprising a seriesof backing chambers, and means for coupling said thin, flexible sheetunderlying the backing surface to another thin, flexible sheetintermediate said bottom thin, flexible sheet and said backing surface,which defines with said backing surface the series of backing chambers,at spaced positions substantially across the extent of said area ofperforations to provide individual segments to said at least one plenumchamber to prevent excessive slack in said bottom thin, flexible sheet..Iaddend..Iadd.50. The flexible air chamber-type air pallet as claimedin claim 48, wherein said at least one row of tubes is sealed from saidat least one plenum chamber, and means are provided for separatelysupplying compressed air to said at least one row of tubes from thatsupplied to said at least one plenum chamber. .Iaddend..Iadd.51. Theflexible air chamber-type air pallet as claimed in claim 50, furthercomprising a pressure relief valve operatively coupled to said at leastone row of tubes and set to prevent the pressure therein from reaching alevel inducing capillary closure of the patient supported by said airpallet. .Iaddend..Iadd.52. The flexible air chamber-type air pallet asclaimed in claim 51, wherein said pressure relief valve is a variablyadjustable valve such that said at least one row of tubes can be lightlyair pressurized to form a highly supple comfortable air mattress forsupporting a patient thereon over long periods of time without trauma,while providing therapy to said patient. .Iaddend..Iadd.53. The flexibleair chamber-type air pallet as claimed in claim 48, wherein at least oneof said tubes constituting said rigid backing surface carries said airinlet means at one end thereof opening directly thereto, and wherein atan opposite end thereof, an air flow port opens to an integral linkedtube of another row of tubes to permit flow of low pressure air flowfrom one tube of one of said rows to said tube of another row via saidair flow port and wherein the cross-sectional area of said air flow portis substantially less than the cross-sectional area of said air inletmeans such that said one tube of said one linked row is at a higherpressure than said other tube of said another linked row of tubes..Iaddend..Iadd.54. The flexible air chamber-type air pallet as claimedin claim 48, wherein openings are provided within said tubes of one rowwhich open directly into tubes of an adjacent row, and wherein saidtubes of said one or said adjacent row have further openings which opendirectly into the plenum chamber, and wherein at least one of said tubesof one of said rows carries air inlet means at one end thereof openingdirectly thereto, such that said air pallet constitutes a flow throughsoft pad with said flow of air being through said tubes of integrallinked rows, and through said plenum chamber to effect said means forsubstantially restricting lateral shrinkage of the plenum chamber, whileproviding simultaneously said air film. .Iaddend..Iadd.55. The flexibleair chamber-type air pallet as claimed in claim 48, further comprisingmeans for eliminating trauma to the head and neck of a patient supportedon the air pallet induced by jolts received from unequal airpressurization of the row of tubes forming the flexible backingchambers. .Iaddend..Iadd.56. The flexible air chamber-type air pallet asclaimed in claim 55, wherein said means for eliminating trauma to thehead and neck of a patient comprises air flow paths between the ends ofthe tubes and the opposing edge of the air pallet, said air flow pathhaving a pre-determined minimum dimension. .Iaddend..Iadd.57. Theflexible air chamber-type air pallet as claimed in claim 25, whereinsaid air pallet includes an intermediate thin, flexible sheet interposedbetween said first thin, flexible sheet and said second thin, flexiblesheet which with said first thin, flexible sheet defines a series ofbacking chambers for supporting said load. .Iaddend..Iadd.58. Theflexible air chamber-type air pallet as claimed in claim 57, furthercomprising a second intermediate thin, flexible sheet edge sealed tosaid first intermediate thin, flexible sheet to opposite sides thereof,and defining a backing member cavity, and wherein a generally rigidbacking member is carried within said cavity and comprises part of saidmeans for substantially restricting lateral shrinkage of said plenumchamber over at least the width of said perforated portion of saidbottom thin flexible sheet. .Iaddend..Iadd.59. The flexible airchamber-type air pallet as claimed in claim 58, wherein said series ofbacking chambers are sealed from said plenum chambers, and means areprovided for separately supplying compressed air to said series ofbacking chambers from that supplied to said plenum chambers..Iaddend..Iadd.60. The flexible air chamber-type air pallet as claimedin claim 59, further comprising a pressure relief valve operativelycoupled to said series of backing chambers and set to prevent thepressure therein from reaching a level inducing capillary closure of thepatient supported by said air pallet. .Iaddend..Iadd.61. The flexibleair chamber-type air pallet as claimed in claim 60, wherein saidpressure relief valve is a variably adjustable valve such that saidseries of backing chambers can be lightly air pressurized to form ahighly supple comfortable air mattress for supporting a patient thereonover long periods of time without trauma, while providing therapy tosaid patient. .Iaddend..Iadd.62. The flexible air chamber-type airpallet as claimed in claim 58, further comprising another thin flexiblesheet sealed to the top thin flexible sheet along the edges thereof andsealed along lines extending transversely across said air pallet to thetop thin flexible sheet, including a perforated area having a pluralityof closely spaced small diameter pinhole-type perforations openingupward towards the load for creating a second air bearing, defining anupper plenum chamber directly beneath the patient supported by said airpallet. .Iaddend..Iadd.63. The flexible air chamber-type air pallet asclaimed in claim 62, wherein said upper plenum chamber, when pressurizedfrom a source of compressed air, provides sufficient lubrication forpatient positioning on the air pallet. .Iaddend..Iadd.64. The flexibleair chamber-type air pallet as claimed in claim 62, wherein said upperplenum chamber, upon pressurization from a separate source of compressedair, can be utilized to supply a medicament in vapor form upwards aboutthe patient supported by the air pallet. .Iaddend..Iadd.65. The flexiblefilm air chamber-type air pallet as claimed in claim 26, wherein saidflexible, generally planar backing surface is comprised of at least atop thin, flexible sheet and a bottom thin, flexible sheet being sealedto each other and defining a series of flexible backing chambersdirectly overlying said at least one plenum chamber. .Iaddend..Iadd.66.The flexible film air chamber-type air pallet as claimed in claim 65,wherein said means for preventing hotdogging and load instability, formaintaining said backing surface generally parallel to said developedair film, for limiting shrink of the air pallet, and for rendering saidbacking surface sufficiently rigid during air pressurization of said atleast one plenum chamber comprises at least two integral, linkedvertical rows of backing chambers with a first row being laterallyoffset with respect to a second row such that the centers of thechambers in the first row are aligned with abutting peripheries ofchambers of the second row and adjacent chambers of said two rows havinga common wall under pressurization to opposite sides being rendered tautand rigid and means for coupling said thin, flexible sheet underlyingthe backing surface to said backing chambers at spaced positionssubstantially across the extent of said area of perforations to provideindividual segments to said at least one plenum chamber to preventexcessive slack in said bottom thin, flexible sheet. .Iaddend..Iadd.67.The flexible film air chamber-type air pallet as claimed in claim 65,wherein said series of backing chambers are sealed from said plenumchamber, and means are provided for separately supplying compressed airto said series of backing chambers from that supplied to said at leastone plenum chamber. .Iaddend..Iadd.68. The flexible film airchamber-type air pallet as claimed in claim 67, further comprising apressure relief valve operatively coupled to said series of backingchambers and set to prevent the pressure therein from reaching a levelinducing capillary closure of the patient supported by said air pallet..Iaddend..Iadd.69. The flexible film air chamber-type air pallet asclaimed in claim 68, wherein said pressure relief valve is a variablyadjustable valve such that said series of backing chambers can belightly air pressurized to form a highly supple comfortable air mattressfor supporting a patient thereon over long periods of time withouttrauma, while providing therapy to said patient. .Iaddend..Iadd.70. Theflexible film air chamber-type air pallet as claimed in claim 65,wherein at least one of said backing chambers constituting said backingsurface carries said air inlet means at one end thereof opening directlythereto, and wherein at an opposite end thereof, an air flow port opensto an integral linked chamber of another row of backing chambers topermit flow of low pressure air flow from one chamber of one of saidrows to said chamber of another row via said air flow port and whereinthe cross-sectional area of said air flow port is substantially lessthan the cross-sectional area of said air inlet means such that said onechamber of said one linked row is at a higher pressure than said otherchamber of said another linked row of backing chambers..Iaddend..Iadd.71. The flexible film air chamber-type air pallet asclaimed in claim 65, wherein openings are provided within said backingchambers of one row which open directly into backing chambers of theadjacent row, and wherein said chambers of said one or said adjacent rowhave further openings which open directly into the plenum chamber, andwherein at least one of said backing chambers of one of said rowscarries air inlet means at one end thereof opening directly thereto,such that said air pallet constitutes a flow through soft pad with saidflow of air being through said backing chambers of integral linked rows,and through said plenum chamber to effect said means for substantiallyrestricting lateral shrinkage of the plenum chamber, while providingsimultaneously said air film. .Iaddend..Iadd.72. The flexible film airchamber-type air pallet as claimed in claim 65, wherein said series ofbacking chambers generally extend longitudinally along the air pallet..Iaddend..Iadd.73. The flexible film air chamber-type air pallet asclaimed in claim 65, wherein said series of backing chambers generallyextend laterally across the air pallet. .Iaddend..Iadd.74. The flexiblefilm air chamber-type air pallet as claimed in claim 26, furthercomprising another thin flexible sheet sealed to the generally planarbacking surface along the edges thereof and sealed along lines extendingtransversely across said air pallet to the backing surface, including aperforated area having a plurality of closely spaced small diameterpinhole-type perforations opening upward towards the load for creating asecond air bearing, defining an upper plenum chamber directly beneaththe patient supported by said patient mover air pallet..Iaddend..Iadd.75. The flexible film air chamber-type air pallet asclaimed in claim 74, wherein said upper plenum chamber, when pressurizedfrom a source of compressed air, provides sufficient lubrication forpatient positioning on the air pallet. .Iaddend..Iadd.76. The flexiblefilm air chamber-type air pallet as claimed in claim 74, wherein saidupper plenum chamber, upon pressurization from a separate source ofcompressed air, can be utilized to supply a medicament in vapor formupwards about the patient supported by the air pallet..Iaddend..Iadd.77. The flexible film air chamber-type air pallet asclaimed in claim 65, further comprising means for eliminating trauma tothe head and neck of a patient supported on the air pallet induced byjolts received from unequal air pressurization of the series of flexiblebacking chambers. .Iaddend..Iadd.78. The flexible film air chamber-typeair pallet as claimed in claim 77, wherein said means for eliminatingtrauma to the head and neck of a patient comprises air flow pathsbetween the ends of the tubes and the opposing edge of the air pallet,said air flow path having a pre-determined minimum dimension. .Iaddend.